Hi, well I got my old MPS-801 Commodore printer going. But now there is a new problem with LISTing programs to the printer:
I type:
OPEN 3,4
CMD3
and the printer responds with
READY.
Then I type:
LIST
Mostly I then get a carriage return and nothing else. Sometimes I'll get the first line of the program or two. VERY RARELY I'll get the whole listing.
It's like the printer is hanging.
BUT the strange thing is, self test mode in this printer works fine. Also I tried printing a letter from HESWriter and the whole page came out fine. Also if I just send "live" commands to the printer like:
CMD3
PRINT "HELLO"
It always works just fine.
It seems to have problems with LISTING.
I've tried hooking the printer directly to the VIC-20 (instead of daisychaining it through the floppy drive). I've tried a different serial cable, too.
Can anyone tell me what is happening here? The only theory I can come up with is that some of the buffer RAM in the printer itself has gone bad, and when it has to deal with large dumps of characters (like listings) it crashes.
Any suggestions or advice to offer. It's a bit discouraging, as it's my only working original Commodore printer (or I thought it was).
Printer problem. Please help.
Well, it's definitely something wrong with the MPS-801. I coaxed my VIC-1525 printer into a semi-working state (print head motor is weak and a bit of lubricant on the rails helped it) and it works just fine and behaves normally. So it's not the VIC-20 that is the problem.
I tested the MPS-801 again, trying to LIST to the printer a 10 line program. Funny thing was, it kept stopping at exactly the same line in the program each time. It would just hang after that line, doing nothing. I would be forced to hit RUNSTOP/RESTORE on the VIC and then do a CLOSE 3,4.
But the WIERDEST thing was, if I immediately did the following:
OPEN 3,4
CMD 3
The printer would print another partial line of the program listing and then do a couple carriage returns and display:
READY.
I tried this three times with exactly the same results.
Needless to say, listing disk directories also resulted in a similar problem as above. No listing, but when I CLOSEd and re-OPENed the printer it spit out one partial line of the disk's directory and then gave me a READY prompt.
I think it's also important to note that I never get garbled characters. What it does manage to print out is accurate. Also, the printer never hangs in the middle of a line....it always hangs after a carriage return (i.e. at the beginng of a LIST it does a single carriage return and I get nothing else, or if it does a partial listing it will always complete a line or two or three and then do a carriage return and just stop).
This really makes me thing there is something wrong with this printer's internal buffer. If it is the RAM chips, are they easily replacable? Does anyone have an old MPS-801 motherboard they would be willing to sell me?
I tested the MPS-801 again, trying to LIST to the printer a 10 line program. Funny thing was, it kept stopping at exactly the same line in the program each time. It would just hang after that line, doing nothing. I would be forced to hit RUNSTOP/RESTORE on the VIC and then do a CLOSE 3,4.
But the WIERDEST thing was, if I immediately did the following:
OPEN 3,4
CMD 3
The printer would print another partial line of the program listing and then do a couple carriage returns and display:
READY.
I tried this three times with exactly the same results.
Needless to say, listing disk directories also resulted in a similar problem as above. No listing, but when I CLOSEd and re-OPENed the printer it spit out one partial line of the disk's directory and then gave me a READY prompt.
I think it's also important to note that I never get garbled characters. What it does manage to print out is accurate. Also, the printer never hangs in the middle of a line....it always hangs after a carriage return (i.e. at the beginng of a LIST it does a single carriage return and I get nothing else, or if it does a partial listing it will always complete a line or two or three and then do a carriage return and just stop).
This really makes me thing there is something wrong with this printer's internal buffer. If it is the RAM chips, are they easily replacable? Does anyone have an old MPS-801 motherboard they would be willing to sell me?
If you suspect the problem is with carriage return, wouldn't the printer freeze for single PRINT statements too, assuming they make the printer do a carriage return?
Maybe you can make a test program that feeds a lot of data to the printer, something like this
10 OPEN1,4
15 FORI=1TO10:FORJ=1TO80
17 PRINT#1,CHR$(65+INT(RND(1)*26));
18 NEXTJ,I
20 CLOSE1
I believe that would dump ten full lines of random letters, a bit like a self test mode but not sequential. When the printer reaches the end of a line, does it automatically return to the first position on next row? It was ages ago since I owned a MPS-801, so I can't recall how it works. Frankly, it is one of the pieces of C= equipment I'm happy I sold, although it worked perfectly.
Maybe you can make a test program that feeds a lot of data to the printer, something like this
10 OPEN1,4
15 FORI=1TO10:FORJ=1TO80
17 PRINT#1,CHR$(65+INT(RND(1)*26));
18 NEXTJ,I
20 CLOSE1
I believe that would dump ten full lines of random letters, a bit like a self test mode but not sequential. When the printer reaches the end of a line, does it automatically return to the first position on next row? It was ages ago since I owned a MPS-801, so I can't recall how it works. Frankly, it is one of the pieces of C= equipment I'm happy I sold, although it worked perfectly.
Anders Carlsson
I don't think it's a problem with the carriage return. I just think that at point the printer cannot deal with large dumps of data (due to corrupt memory maybe) and craps out.carlsson wrote:If you suspect the problem is with carriage return, wouldn't the printer freeze for single PRINT statements too, assuming they make the printer do a carriage return?
It is funny that it will always finish the latest line and give a carriage return before hanging, though.
If I do direct individual PRINT commands to the printer, it is always very reliable. It's only when I try sending large amounts of data (i.e. listing programs, etc.) that it almost always hangs (sometimes right away, sometimes after one or two lines are printed). It never hangs in the middle of a line either, but always finishes the line and does a carriage return.
Thanks! I will try that.Maybe you can make a test program that feeds a lot of data to the printer
I understand. In the 1980's I hated my MPS801 and was overjoyed to replace it with a NLQ printer. However, now I look back at it as kind of cute primitive device. I like the industrial crude look of its characters. It's just a nostalgia thing, and I like to have a VIC-20 setup that uses as much original Commodore hardware as possible.It was ages ago since I owned a MPS-801, so I can't recall how it works. Frankly, it is one of the pieces of C= equipment I'm happy I sold, although it worked perfectly.
In the meantime I have an inkjet printer hooked up to the VIC with a SUPER-GRAPHIX JR. interface. It works very well, and the printing is fast and sharp, but somehow it's not just the same. (no endearing impact printer screaming noise when printing
)Sure, from a collecting point of view one wants one or more printers, but from a user's point of view (which I think fits me better), I have little use of a matrix printer. Maybe print listings, but since there is no magazine to publish them, and there are other ways to archive or detokenize a Basic listing, it would be a waste of desk space for me today. Disk directories (and perhaps listings too) can be read on a PC, fed through a word processor and printed on my laser if I need them.
Anders Carlsson
I am very lucky in that many people have given me their tractor feed paper, and i find having a commodore printer connected to my vic to be extremely efficient for my purposes.
i would find it very frustrating not having a printer connected to my vic, as i use it everytime i program.
i would have to say that i use the printer as much as i use the disk drive, as a storage device.
and i use tape for my backups
i would find it very frustrating not having a printer connected to my vic, as i use it everytime i program.
i would have to say that i use the printer as much as i use the disk drive, as a storage device.
and i use tape for my backups
Well, I opened up my MPS-801 and noted all the chip numbers:
Does anyone know if any of the above could be the RAM chip(s)? I have enough skill to do a simple swap and replace it, but I'm no good at telling what these chips do. Thanks!
PS: I took a photo of the board. If that would be more helpful I'll post it.
- HP74LS74AP - Dual D-Type Positive Edge-Triggered Flip Flops (with Preset & Clear)
SN74LS373N - Octal D-Type Transparent Latches with 3-state outputs
ULN2003A - High Voltage, High current darlington transistor arrays.
MBL8039H - All I could find was it was made by Fujitsu (a large 40 pin IC - largest on the board)
M74LS04P - HEX inverter
M53206P - couldn't identify this chip on the internet
Does anyone know if any of the above could be the RAM chip(s)? I have enough skill to do a simple swap and replace it, but I'm no good at telling what these chips do. Thanks!
PS: I took a photo of the board. If that would be more helpful I'll post it.
The M53206P is Mitsubishi's part number for the plain old 74LS06 Hex inverting buffer with open collector outputs.
http://www.datasheets.org.uk/specsheet.php?part=M53206P
I had to replace one of these in my Gemini Star 10X printer when a buddy of mine knocked over a beer and the contents spilled into printer
The MBL8039H is an 8 bit controller which appears to have a limited amount of built in ram.
http://www.xs4all.nl/~ganswijk/chipdir/giicm/8039.txt
If I was going with shot gun approach of replacing chips, I would start with 74ls06 (M53206P). This is the direct interface chip to external serial bus cable. Who knows. maybe somebody spilled a beer into your printer before you got it.
If the problem was not resolved with 74ls06 replacement, I would follow this with the other cheap and easy attainable 74ls04, 74ls74, and 74ls373.
The ULN2003A chip(s) are unlikely bad otherwise you would be missing row(s) of pixles in printed characters.
http://www.datasheets.org.uk/specsheet.php?part=M53206P
I had to replace one of these in my Gemini Star 10X printer when a buddy of mine knocked over a beer and the contents spilled into printer
The MBL8039H is an 8 bit controller which appears to have a limited amount of built in ram.
http://www.xs4all.nl/~ganswijk/chipdir/giicm/8039.txt
If I was going with shot gun approach of replacing chips, I would start with 74ls06 (M53206P). This is the direct interface chip to external serial bus cable. Who knows. maybe somebody spilled a beer into your printer before you got it.
If the problem was not resolved with 74ls06 replacement, I would follow this with the other cheap and easy attainable 74ls04, 74ls74, and 74ls373.
The ULN2003A chip(s) are unlikely bad otherwise you would be missing row(s) of pixles in printed characters.
Mega-Cart: the ultimate cartridge for your Commodore Vic-20I just bought a bunch of tractor feed paper from Staples (Business Depot in Canada). They didn't have any of the 500 sheet packs, so I had to buy a huge box of 2200 sheets which cost $20. I should have enough tractor feed paper to last me 10 years! Unfortunately, it wasn't until after I bought it (to test my MPS-801) that I discovered the printer has a problem...vic user wrote:I am very lucky in that many people have given me their tractor feed paper, and i find having a commodore printer connected to my vic to be extremely efficient for my purposes.
i would find it very frustrating not having a printer connected to my vic, as i use it everytime i program.
i would have to say that i use the printer as much as i use the disk drive, as a storage device.
and i use tape for my backups
Well folks. I have some good news. My MPS-801 printer seems to work now.
When I removed the circuit board to identify all the chips, I also took a moment to reseat the only socketed chip - the EPROM.
I also removed and re-connected all the cables from the board, as well as removed and re-soldered the large capacitors (I originally thought they were leaking but some more experienced people on this board taught me it was just hot glue).
So one of the above actions must have fixed the problem. I suspect it was the re-seating of the EPROM.
So last night I printed several long listings and disk directories and I had no lockups.
I am very happy about this
When I removed the circuit board to identify all the chips, I also took a moment to reseat the only socketed chip - the EPROM.
I also removed and re-connected all the cables from the board, as well as removed and re-soldered the large capacitors (I originally thought they were leaking but some more experienced people on this board taught me it was just hot glue).
So one of the above actions must have fixed the problem. I suspect it was the re-seating of the EPROM.
So last night I printed several long listings and disk directories and I had no lockups.
I am very happy about this