Thermal printer DSR Hacking help wanted

[+FarmerPotato]

On 4/14/2020 at 5:09 PM, Tursi said:

It looks like it's setting the CRU timer to the maximum possible value - maybe initializing a timeout?

 

Not sure why zero CRU bit 3... zeroing bit 0 is probably just to ensure a known starting state. The LDCR will switch to timer mode when bit 0 gets a 1, and then next 14 bits will fill the timer register. The last SBZ exits timer mode and starts counting.

 

Edit: ah, bit 3 is the timer interrupt bit

 

 

Oh yeah.

The timer generates interrupt 3.  So the interrupt handler won't fire, and I guess the device just loops watching for it. 

 

[+acadiel]

On what I call the "data" side of the Thermal printer PCB are:

 

U10 SN74LS126AN - "QUADRUPLE BUS BUFFERS WITH 3-STATE OUTPUTS"

U11 SN74LS244N - "Octal Buffers And Line Drivers With 3-State Outputs"

U12 CN36006N 8116 S 1501709-2 - 4K DSR ROM

U13 SN7407N - "HEX BUFFER DRIVER"

U14/U15 2x SN74LS138 - "3 LINE TO 8-LINE DECODER/DEMULTIPLEXER"

 

The Thermal Printer side of the circuit has:

U1/U2/U3 - ULN2003AN - High Voltage, High Current, Darlington Transistor Arrays

U4/U5/U6/U7 4X SN74LS259N - "8 Bit Addressable Latch"

U8 SN74LS (can't read - maybe 122?)

U9 74LS02N - Quadrupule 2-input positive NOR gates

 

[+InsaneMultitasker]

On 4/14/2020 at 3:12 PM, acadiel said:

Not that I see.  It's just a bunch of logic chips and a 4K DSR ROM (I'm thinking it's a 2532 pinout if I'm not mistaken, so I need to get a 2764 to 2532 adapter.)

 

When I disassembled the 8K ROM image, I noticed that the DSR is only 2K.  And it is pretty well crammed into that 2k window... did TI produce a 2K ROM?  My thought was they created the DSR with 2K in mind but used 4K hardware?

[+acadiel]

2 minutes ago, InsaneMultitasker said:

When I disassembled the 8K ROM image, I noticed that the DSR is only 2K.  And it is pretty well crammed into that 2k window... did TI produce a 2K ROM?  My thought was they created the DSR with 2K in mind but used 4K hardware?

 

I'm going to socket it this weekend and try a 2532 and see if it works. 

 

I can only guess - nobody has ever found any schematics or service manual for the TP. 

 

[+mizapf]

Disassembling a mere 2K should be a rather simple job.

[+InsaneMultitasker]

3 minutes ago, mizapf said:

Disassembling a mere 2K should be a rather simple job.

I disassembled and commented a good portion of it.  See post #22 if you'd like to gnaw on it for a while.

[+mizapf]

Tempting...

(Actually, while doing all that emulation work, a surprising amount of work piled up behind my back...)

[+FarmerPotato]

On 4/16/2020 at 1:42 PM, InsaneMultitasker said:

When I disassembled the 8K ROM image, I noticed that the DSR is only 2K.  And it is pretty well crammed into that 2k window... did TI produce a 2K ROM?  My thought was they created the DSR with 2K in mind but used 4K hardware?

 

Do you mean, did they make 2K ROM chips? The TMS4800 was a 2Kx8 mask ROM. The 2516 and 2716 EPROMs offered 2Kx8.

 

According to the 1975 data book, you would deliver your ROM content on punch-cards, encoded in octal digits.

1975   https://archive.org/details/bitsavers_tidataBookorMemoryDataBook_9924035/page/n111/mode/2up/search/2k

 

The 1980 MOS Memory Data Book lists:

2516 2k x 8 EPROM with single +5V supply
2716 2k x 8 EPROM required -5V, +5V, +12V for normal use, but overall a bit less power.
4732 4k x 8 ROM was the smallest ROM. 

1980 https://archive.org/details/bitsavers_tidataBookDataBookforDesignEngineers_5563221

 

 

By 1984, the 2716 was gone, 2516 was still around, and only one power supply was needed by the 2732 and up.

2516 still around
2716 gone. Good riddance.
2732 4k x 8 with single +5V supply

1984   https://archive.org/details/bitsavers_tidataBook984_15352413/page/n11/mode/2up

 

So 2k x 8 was on its way out even in 1980.

 

 

 

[+acadiel]

On 4/13/2020 at 7:33 PM, Tursi said:

If you can, give this a try. It looks like the ROM is only 4k, so you may need a 4k EPROM instead of 8k.

 

There seem to be only two places that verify the record length. I changed them to pull the record length from >4001 - so the second byte of the ROM, and set this one to >1E (ie: 30).

 

Beyond that, I can only say it doesn't crash. Classic99 doesn't emulate the hardware of the Thermal Printer nor do I know how it works, so I can't check it formatted the output correctly. But it loads the PAB and then times out gracefully. If the PAB is right, based on what I see above, good chance the rest will be.

TIThermalMod.zip 2.17 kB · 9 downloads

 

The thermal printer mod appears to work when printing a 40 character line from BASIC.  A-Maze-ing also works!

 

 

[+OLD CS1]

Never knew A-Maze-Ing did that...

[JB]

48 minutes ago, OLD CS1 said:

Never knew A-Maze-Ing did that...

I was thinking the same thing. I'm a-maze-d.

[+FarmerPotato]

9 hours ago, acadiel said:

The thermal printer mod appears to work when printing a 40 character line from BASIC.  A-Maze-ing also works!

 

 

 

I love this. A*Maze*Ing was my first module.  I can just imagine another childhood containing these tiny printed mazes. (How about a Complex maze?)

Thanks!

 

[+acadiel]

12 hours ago, FarmerPotato said:

I love this. A*Maze*Ing was my first module.  I can just imagine another childhood containing these tiny printed mazes. (How about a Complex maze?)

Thanks!

 

An older test I did with narrower paper...

[fabrizio]

On 14/4/2020 at 20:43, acadiel said:

Eccezionale! Grazie! Devo entrare nell'unità della stampante termica delle `` parti '' che ho e capire qual è il pinout della ROM: potrebbe effettivamente essere 4K (su cui posso semplicemente scrivere due volte e collegarmi a una EPROM 8K dopo aver spostato perni.)

 

Non esiste un manuale tecnico sulla stampante termica, quindi cercherò il controller del disco e le piedinature RS232 per le loro ROM DSR per avere un'idea di quali sono i pin quando li sostituisco. Il primo passo sarà inserire una presa dopo aver usato il mio dissaldatore.

 

Pinout RS232 della ROM 4K di Fred:   http://www.ti99-geek.nl/Projects/ti99hdx/Files/RS232_Ram.txt

 

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