P2000T - Revision history

Mahjongg: /* 30 October, 2017 74LS145 replaced, nothing changed, a few keys still produce garbage after the correct character */

2017-11-01T16:22:05Z

30 October, 2017 74LS145 replaced, nothing changed, a few keys still produce garbage after the correct character

← Older revision		Revision as of 16:22, 1 November 2017
Line 128:		Line 128:
	I'm marking this project as finished. I have repaired the keyboard, so I could run the BASIC DEMO tape in Revspace, as was my goal, and that is all I want to do with the P2000T.		I'm marking this project as finished. I have repaired the keyboard, so I could run the BASIC DEMO tape in Revspace, as was my goal, and that is all I want to do with the P2000T.

	I wrote a few short basic programs, and tried to save one to cassette, (I circumvented the ¨geen stopje¨ write protect error with a piece of scotch tape), but probably the tapes had no space left, as they gave ¨Cassette fout E¨ on both sides, and I have no new empty ~~dictaphone~~ tape.		I wrote a few short basic programs, and tried to save one to cassette, (I circumvented the ¨geen stopje¨ write protect error with a piece of scotch tape), but probably the tapes had no space left, as they gave ¨Cassette fout E¨ on both sides, and I have no new empty Dictaphone tape, so I could save not even short programs.

	I can see why there are very few demo programs for P2000T emulators ~~and such~~, as its very hard to convert such tapes to a computer (.TAP) file or something like that. Still emulators do exist, (like MESS) and there are a few YouTube ~~videoś~~ showing P2000T programs, (running on emulators, no doubt,but very few.		I can see why there are very few demo programs for P2000T emulators, as its very hard to convert such tapes to a computer (.TAP) file or something like that. Still emulators do exist, (like MESS) and there are a few YouTube video's showing P2000T programs, (running on emulators, no doubt) but very few.

Mahjongg: /* 12 September, 2017 received a P2000T in box */

2017-10-31T23:33:22Z

12 September, 2017 received a P2000T in box

← Older revision		Revision as of 23:33, 31 October 2017
Line 8:		Line 8:

	== 12 September, 2017 received a P2000T in box ==		== 12 September, 2017 received a P2000T in box ==
	The Philips P200T I received from Benadski as a donation, came in a plain looking cardboard with large brown spill marks, it seemed sometime in the past had spilled a lot of coffee (or something like that) over it, and the computer looked like a mess, so I disassembled the computers, in an an attempt to estimate the damage the coffee had done. Remarkably the main board was as new, but the keyboard PCB wasn't as lucky, as the coffee had spilled all over it. After cleaning it thoroughly I assembled it, and took it home to test if it was working, which it did, but unfortunately I couldn't test if there was damage to the keyboard!		The Philips P200T I received from Benadski as a donation, came in a plain looking cardboard with large brown coffee spill marks, it seemed sometime in the past had spilled a lot of coffee (or something like that) over it, and the computer looked like a mess, so I disassembled the computers, in an an attempt to estimate the damage the coffee had done. Remarkably the main board was as new, but the keyboard PCB wasn't as lucky, as the coffee had spilled all over it. After cleaning it thoroughly I assembled it, and took it home to test if it was working, which it did, but unfortunately I couldn't test if there was damage to the keyboard!
	[[File:IMG 7027.jpg\|thumb\|The startup screen of a P2000T without BASIC cartrdge]]		[[File:IMG 7027.jpg\|thumb\|The startup screen of a P2000T without BASIC cartrdge]]
	It also did not come with a manual, or anything else, beyond a power cable. Especially unfortunately was that the essential BASIC cartridge was missing, as was the transparent cover over the what I presume was a place to stick some indexing card or maybe just a logo, as can be seen in the project picture on the right here.		It also did not come with a manual, or anything else, beyond a power cable. Especially unfortunately was that the essential BASIC cartridge was missing, as was the transparent cover over the what I presume was a place to stick some indexing card or maybe just a logo, as can be seen in the project picture on the right here.

Mahjongg: /* 30 October, 2017 74LS145 replaced, nothing changed, some keys still produce garbage after the correct character */

2017-10-31T23:32:30Z

30 October, 2017 74LS145 replaced, nothing changed, some keys still produce garbage after the correct character

← Older revision		Revision as of 23:32, 31 October 2017
Line 123:		Line 123:
	In time I will repair the broken 74LS145 chip, but I'm not in a hurry with that right now.		In time I will repair the broken 74LS145 chip, but I'm not in a hurry with that right now.

	== 30 October, 2017 74LS145 replaced, nothing changed, ~~some~~ keys still produce garbage after the correct character ==		== 30 October, 2017 74LS145 replaced, nothing changed, a few keys still produce garbage after the correct character ==
	Well, I replaced the 74LS145 decoder, and it did not matter! Something other than the decoder is causing this problem, and I have no clue what it could be. Now I could try to get to the bottom of this problem by using an oscilloscope to try to find out exactly what is happening when the keys repeat, but actually I don't care. I regretfully give up in this case. The keyboard as is, is workable now. The problem IS in the main-board, not in the keyboard. As exchanging the keyboard for another one has shown. The problem could be systematic too, indicating a weakness in the design.		Well, I replaced the 74LS145 decoder, and it did not matter! Something other than the decoder is causing this problem, and I have no clue what it could be. Now I could try to get to the bottom of this problem by using an oscilloscope to try to find out exactly what is happening when the keys repeat, but actually I don't care. I regretfully give up in this case. The keyboard as is, is workable now. The problem IS in the main-board, not in the keyboard. As exchanging the keyboard for another one has shown. The problem could be systematic too, indicating a weakness in the design.

Mahjongg: /* 30 October, 2017 74LS145 replaced, nothing changed, some keys still produce garbage after the correct text */

2017-10-31T23:32:11Z

30 October, 2017 74LS145 replaced, nothing changed, some keys still produce garbage after the correct text

← Older revision		Revision as of 23:32, 31 October 2017
Line 123:		Line 123:
	In time I will repair the broken 74LS145 chip, but I'm not in a hurry with that right now.		In time I will repair the broken 74LS145 chip, but I'm not in a hurry with that right now.

	== 30 October, 2017 74LS145 replaced, nothing changed, some keys still produce garbage after the correct ~~text~~ ==		== 30 October, 2017 74LS145 replaced, nothing changed, some keys still produce garbage after the correct character ==
	Well, I replaced the 74LS145 decoder, and it did not matter! Something other than the decoder is causing this problem, and I have no clue what it could be. Now I could try to get to the bottom of this problem by using an oscilloscope to try to find out exactly what is happening when the keys repeat, but actually I don't care. I regretfully give up in this case. The keyboard as is, is workable now. The problem IS in the main-board, not in the keyboard. As exchanging the keyboard for another one has shown. The problem could be systematic too, indicating a weakness in the design.		Well, I replaced the 74LS145 decoder, and it did not matter! Something other than the decoder is causing this problem, and I have no clue what it could be. Now I could try to get to the bottom of this problem by using an oscilloscope to try to find out exactly what is happening when the keys repeat, but actually I don't care. I regretfully give up in this case. The keyboard as is, is workable now. The problem IS in the main-board, not in the keyboard. As exchanging the keyboard for another one has shown. The problem could be systematic too, indicating a weakness in the design.

Mahjongg: /* 30 October, 2017 74LS145 replaced, nothing changed */

2017-10-31T23:31:41Z

30 October, 2017 74LS145 replaced, nothing changed

← Older revision		Revision as of 23:31, 31 October 2017
Line 123:		Line 123:
	In time I will repair the broken 74LS145 chip, but I'm not in a hurry with that right now.		In time I will repair the broken 74LS145 chip, but I'm not in a hurry with that right now.

	== 30 October, 2017 74LS145 replaced, nothing changed ==		== 30 October, 2017 74LS145 replaced, nothing changed, some keys still produce garbage after the correct text ==
	Well, I replaced the 74LS145 decoder, and it did not matter! Something other than the decoder is causing this problem, and I have no clue what it could be. Now I could try to get to the bottom of this problem by using an oscilloscope to try to find out exactly what is happening when the keys repeat, but actually I don't care. I regretfully give up in this case. The keyboard as is, is workable now. The problem IS in the main-board, not in the keyboard. As exchanging the keyboard for another one has shown. The problem could be systematic too, indicating a weakness in the design.		Well, I replaced the 74LS145 decoder, and it did not matter! Something other than the decoder is causing this problem, and I have no clue what it could be. Now I could try to get to the bottom of this problem by using an oscilloscope to try to find out exactly what is happening when the keys repeat, but actually I don't care. I regretfully give up in this case. The keyboard as is, is workable now. The problem IS in the main-board, not in the keyboard. As exchanging the keyboard for another one has shown. The problem could be systematic too, indicating a weakness in the design.

Mahjongg at 23:30, 31 October 2017

2017-10-31T23:30:14Z

← Older revision		Revision as of 23:30, 31 October 2017
Line 3:		Line 3:
	\|Picture=Philips-p2000t.jpg		\|Picture=Philips-p2000t.jpg
	\|Omschrijving= A new addition to my collection, to cleanup and get working		\|Omschrijving= A new addition to my collection, to cleanup and get working
	\|Status=~~In progress~~		\|Status=Completed
	\|Contact=Mahjongg		\|Contact=Mahjongg
	}}		}}

Mahjongg: /* 25 October, 2017 found back BASIC Demo cassette and ran all the demo's */

2017-10-31T23:29:16Z

25 October, 2017 found back BASIC Demo cassette and ran all the demo's

← Older revision		Revision as of 23:29, 31 October 2017
Line 122:		Line 122:

	In time I will repair the broken 74LS145 chip, but I'm not in a hurry with that right now.		In time I will repair the broken 74LS145 chip, but I'm not in a hurry with that right now.

			== 30 October, 2017 74LS145 replaced, nothing changed ==
			Well, I replaced the 74LS145 decoder, and it did not matter! Something other than the decoder is causing this problem, and I have no clue what it could be. Now I could try to get to the bottom of this problem by using an oscilloscope to try to find out exactly what is happening when the keys repeat, but actually I don't care. I regretfully give up in this case. The keyboard as is, is workable now. The problem IS in the main-board, not in the keyboard. As exchanging the keyboard for another one has shown. The problem could be systematic too, indicating a weakness in the design.

			I'm marking this project as finished. I have repaired the keyboard, so I could run the BASIC DEMO tape in Revspace, as was my goal, and that is all I want to do with the P2000T.

			I wrote a few short basic programs, and tried to save one to cassette, (I circumvented the ¨geen stopje¨ write protect error with a piece of scotch tape), but probably the tapes had no space left, as they gave ¨Cassette fout E¨ on both sides, and I have no new empty dictaphone tape.

			I can see why there are very few demo programs for P2000T emulators and such, as its very hard to convert such tapes to a computer (.TAP) file or something like that. Still emulators do exist, (like MESS) and there are a few YouTube videoś showing P2000T programs, (running on emulators, no doubt,but very few.

Mahjongg: /* 25 October, 2017 found back BASIC Demo cassette and ran all the demo's */

2017-10-27T14:39:23Z

25 October, 2017 found back BASIC Demo cassette and ran all the demo's

← Older revision		Revision as of 14:39, 27 October 2017
Line 115:		Line 115:
	Found back the micro-cassette tape, it seems I took it with me inside the cartridge compartment of the P2000T to Awesome space where it fell out unnoticed, and I found it back on the solder table where it fell out when I turned over the P2000T to unscrew it. Benadsky noticed it there and informed me he had found it there.		Found back the micro-cassette tape, it seems I took it with me inside the cartridge compartment of the P2000T to Awesome space where it fell out unnoticed, and I found it back on the solder table where it fell out when I turned over the P2000T to unscrew it. Benadsky noticed it there and informed me he had found it there.
	So I went to Utrecht last Saturday, and recovered it, and at home I tested it. Now could get a catalog of files on the tape by pressing "Zoek", (shift 1 on the numerical keypad) found that the initial file on the tape started with "? " followed by the name of the file which indicated it was some kind of main menu program, so I did enter the CLOAD "?" command, which worked, and I could run the BASIC command of the main menu system, from which I could load the other demo's without typing in a lengthy CLOAD command.		So I went to Utrecht last Saturday, and recovered it, and at home I tested it. Now could get a catalog of files on the tape by pressing "Zoek", (shift 1 on the numerical keypad) found that the initial file on the tape started with "? " followed by the name of the file which indicated it was some kind of main menu program, so I did enter the CLOAD "?" command, which worked, and I could run the BASIC command of the main menu system, from which I could load the other demo's without typing in a lengthy CLOAD command.
	Alas, the P2000T sucks in the graphics department, and it is very slow, so the demo's where a bit disappointing, the most interesting being the kaleidoscope with "dots" the size of one character, so very-very coarse !		Alas, the P2000T sucks in the graphics department, and it is very slow, so the demo's where a bit disappointing, the most interesting being the kaleidoscope with "dots" the size of one character, so very-very coarse, just 40 x 25 "pixels" !

	During that demo I could also see the P2000T does not have any video arbitration logic, so it generates what is know as "black snow", that is whenever the CPU writes to video logic it simply gets priority over the video logic, so the video logic simply "blacks out" the screen display, resulting in black sections of the video traces at random locations in the video signal. The only other system that had no video arbitration logic AFAIK was the original TRS-80 model 1.		During that demo I could also see the P2000T does not have any video arbitration logic, so it generates what is know as "black snow", that is whenever the CPU writes to video logic it simply gets priority over the video logic, so the video logic simply "blacks out" the screen display, resulting in black sections of the video traces at random locations in the video signal. The only other system that had no video arbitration logic AFAIK was the original TRS-80 model 1.

Mahjongg: /* 25 October, 2017 found back BASIC Demo cassette and ran all the demo's */

2017-10-27T14:38:00Z

25 October, 2017 found back BASIC Demo cassette and ran all the demo's

← Older revision		Revision as of 14:38, 27 October 2017
Line 115:		Line 115:
	Found back the micro-cassette tape, it seems I took it with me inside the cartridge compartment of the P2000T to Awesome space where it fell out unnoticed, and I found it back on the solder table where it fell out when I turned over the P2000T to unscrew it. Benadsky noticed it there and informed me he had found it there.		Found back the micro-cassette tape, it seems I took it with me inside the cartridge compartment of the P2000T to Awesome space where it fell out unnoticed, and I found it back on the solder table where it fell out when I turned over the P2000T to unscrew it. Benadsky noticed it there and informed me he had found it there.
	So I went to Utrecht last Saturday, and recovered it, and at home I tested it. Now could get a catalog of files on the tape by pressing "Zoek", (shift 1 on the numerical keypad) found that the initial file on the tape started with "? " followed by the name of the file which indicated it was some kind of main menu program, so I did enter the CLOAD "?" command, which worked, and I could run the BASIC command of the main menu system, from which I could load the other demo's without typing in a lengthy CLOAD command.		So I went to Utrecht last Saturday, and recovered it, and at home I tested it. Now could get a catalog of files on the tape by pressing "Zoek", (shift 1 on the numerical keypad) found that the initial file on the tape started with "? " followed by the name of the file which indicated it was some kind of main menu program, so I did enter the CLOAD "?" command, which worked, and I could run the BASIC command of the main menu system, from which I could load the other demo's without typing in a lengthy CLOAD command.
	Alas, the P2000T sucks in the graphics department, and it is very slow, so the demo's where a bit disappointing, the most interesting being the kaleidoscope with "dots" the size of one character, so very coarse !		Alas, the P2000T sucks in the graphics department, and it is very slow, so the demo's where a bit disappointing, the most interesting being the kaleidoscope with "dots" the size of one character, so very-very coarse !

	During that demo I could also see the P2000T does not have any video arbitration logic, so it generates what is know as "black snow", that is whenever the CPU writes to video logic it simply gets priority over the video logic, so the video logic simply "blacks out" the screen display, resulting in black sections of the video traces at random locations in the video signal. The only other system that had no video arbitration logic AFAIK was the original TRS-80 model 1.		During that demo I could also see the P2000T does not have any video arbitration logic, so it generates what is know as "black snow", that is whenever the CPU writes to video logic it simply gets priority over the video logic, so the video logic simply "blacks out" the screen display, resulting in black sections of the video traces at random locations in the video signal. The only other system that had no video arbitration logic AFAIK was the original TRS-80 model 1.

Mahjongg: /* 25 October, 2017 found back BASIC Demo cassette and ran all the demo's */

2017-10-27T14:37:40Z

25 October, 2017 found back BASIC Demo cassette and ran all the demo's

← Older revision		Revision as of 14:37, 27 October 2017
Line 114:		Line 114:
	== 25 October, 2017 found back BASIC Demo cassette and ran all the demo's ==		== 25 October, 2017 found back BASIC Demo cassette and ran all the demo's ==
	Found back the micro-cassette tape, it seems I took it with me inside the cartridge compartment of the P2000T to Awesome space where it fell out unnoticed, and I found it back on the solder table where it fell out when I turned over the P2000T to unscrew it. Benadsky noticed it there and informed me he had found it there.		Found back the micro-cassette tape, it seems I took it with me inside the cartridge compartment of the P2000T to Awesome space where it fell out unnoticed, and I found it back on the solder table where it fell out when I turned over the P2000T to unscrew it. Benadsky noticed it there and informed me he had found it there.
	So I went to Utrecht last Saturday, and recovered it, and at home I tested it. Now could do a enter the CLOAD command, which worked, and I could run the BASIC command of the main menu system, from which I could load the other demo's.		So I went to Utrecht last Saturday, and recovered it, and at home I tested it. Now could get a catalog of files on the tape by pressing "Zoek", (shift 1 on the numerical keypad) found that the initial file on the tape started with "? " followed by the name of the file which indicated it was some kind of main menu program, so I did enter the CLOAD "?" command, which worked, and I could run the BASIC command of the main menu system, from which I could load the other demo's without typing in a lengthy CLOAD command.
	Alas, the P2000T sucks in the graphics department, and it is very slow, so the demo's where a bit disappointing, the most interesting being the kaleidoscope with "dots" the size of one character, so very coarse !		Alas, the P2000T sucks in the graphics department, and it is very slow, so the demo's where a bit disappointing, the most interesting being the kaleidoscope with "dots" the size of one character, so very coarse !

	During that demo I could also see the P2000T does not have any video arbitration logic, so it generates what is know as "black snow", that is whenever the CPU writes to video logic it simply gets priority over the video logic, so the video logic simply "blacks out" the screen display, resulting in black sections of the video traces at random locations in the video signal. The only other system that had no video arbitration logic AFAIK was the original TRS-80 model 1.		During that demo I could also see the P2000T does not have any video arbitration logic, so it generates what is know as "black snow", that is whenever the CPU writes to video logic it simply gets priority over the video logic, so the video logic simply "blacks out" the screen display, resulting in black sections of the video traces at random locations in the video signal. The only other system that had no video arbitration logic AFAIK was the original TRS-80 model 1.
	Well at least I saw that the cassette system still worked, and how long it took (a minute or two or so) to load the first file on the tape ( a few hundred kilobytes), it didn't strike be as very fast, in fact it was simply slow, slower than say the Microdrive of the Sinclair spectrum.
			Well at least I saw that the cassette system still worked, and found out how long it took (a minute or two or so) to load the first file on the tape ( a few hundred kilobytes), it didn't strike be as very fast, in fact it was simply slow, slower than say the Microdrive of the Sinclair spectrum.

	In time I will repair the broken 74LS145 chip, but I'm not in a hurry with that right now.		In time I will repair the broken 74LS145 chip, but I'm not in a hurry with that right now.