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Great. I've checked in a fix that should prevent the debugger from stomping most of the read-activated soft switches.

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One of the things I had been lamenting was that the apple II+ keyboard couldn't type all of the characters. Turns out there was a cool device called the Videx Enhancer II that would do this, and in addition, also provide macro keys. There was also a function key strip that would plug into it called the Videx FunctionStrip.

This board would install in between the keyboard and the apple ii.

It had a 6502 processor on board with 1k of memory to monitor the apple 2 keyboard and pass the keystrokes along.

It's cool that there was great documentation providing full source code and schematics.

I wanted to look at the code and figured out by pausing the apple II driver, I could load the rom file into memory at $1800 and use the mame debugger to do the disassembly.

load "Videx Enhancer II ROM - 2716.BIN",1800

dasm "VidexEnhancer.txt",1800,800


The rom file doesn't exactly match up with the assembly listing given in the manual, but it's pretty close.

[Linked Image from i.imgur.com]

Quote

The following are some of the Enhancer ]['s features:
*Full ASCII keyboard (128 ASCII codes)
*The complete printable ASCII character set —including lower case — may be displayed
*User definable keys — with down loading from disc [section: 5.f]
*Type ahead buffer [section: 5.g]*Auto repeat [section: 5.a.3]
*Fast repeat [section: 5.a.3]
*Normal Apple ][ mode [section: 5.d]
*Typewriter like operation [section: 5.e]
*Shift—lock feature [section: 5.e.1]
*Control — Reset protection (section: 5.c.1]
*Simple installation [chapter two]
*Microprocessor controlled (6500 series)
*Self test diagnostics [section: 5.h]
*A 2716 EPROM is used for on board firmware

*Complete firmware listings [appendix Y]
*Complete schematic [appendix Z]

*Dvorak keyboard option


Your new keyboard Enhancer ][ utilizes a sophisticated microprocessor with its own RAM. Although the Enhancer ][ is more sophisticated than it’s predecessor, the Keyboard & Display Enhancer, it is significantly easier to install. The microprocessor extends the features of the Enhancer ][ beyond those of the original Keyboard & Display Enhancer with features such as user definable keys and a type ahead buffer. The caps lock, caps unlock, shift lock and control — reset features are preserved, thus supporting the normal Apple ][ keyboard as well as a typewriter like mode.


Ul—2716 EFROM (Enhancer ][ Firmware)
U2—6504 Microprocessor (6502 instruction set)
U3—2114 1K x 4 RAM
U4—2114 1K x 4 RAM
U5—74LS05Hex inverter, open collector
U6—74LS373Octal D latch
U7—74LS139Dual 2—4 line decoder
U8—74LS05Hex inverter, open collector
U9—74LS373Octal D latch
U10—74LS374Octal D flip—flop
Ull—Keyboard output
2N3904 — Reset logic

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Why didn't you just use unidasm to disassemble the ROM?

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Because, and I might as well give out the secret: unidasm doesn't actually do anything, it just prints usage text no matter what arguments you give.

Or at least that's my experience.

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Code
./build/mingw-gcc/bin/x64/Debug/unidasm.exe -arch m6805 -skip 0x100 -count 39 -basepc 0x100 roms/Tiger-Heli_with_MCU/68705brian.bin 
100: 9c        rsp
101: a6 ff     lda   #$FF
103: b7 04     sta   $04
105: b7 05     sta   $05
107: b7 01     sta   $01
109: b7 00     sta   $00
10b: a6 00     lda   #$00
10d: b7 06     sta   $06
10f: 15 01     bclr  2, $01
111: a6 73     lda   #$73
113: b7 00     sta   $00
115: 14 01     bset  2, $01
117: 9a        cli
118: 20 fe     bra   $118
11a: 9d        nop
11b: 9d        nop
11c: 9d        nop
11d: 9d        nop
11e: 9d        nop
11f: 9d        nop
120: cd 01 30  jsr   $0130
123: cd 01 50  jsr   $0150
126: 80        rti

Works just fine. As long as you give it a recognised -arch and a filename it will produce disassembly. The usage message tells you you need to give it -arch and a filename.

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I tried it and yes, you can get a disassembly with

./unidasm -arch m6502 -basepc 1800 "../../Videx Enhancer II ROM - 2716.BIN" -lower


There are slight differences where you've got the replacement of addresses with labels.


diff -b unidasmlowercase.txt videxlowercase.txt
216c216
< 1981: a4 a5 ldy $a5
---
> 1981: a4 a5 ldy <arg
955c955
< 1f45: 20 00 fa jsr $fa00
---
> 1f45: 20 00 fa jsr f8rom:mnemr
971c971
< 1f62: c5 d8 cmp $d8
---
> 1f62: c5 d8 cmp <errflg

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Thanks to quart de pomme I now have a Silentype 3 manual!!! Yes! I've been looking for this for so long and it answers a lot of questions about it such as how to vary the intensity of the thermal print as well as the meaning and subtleties of the ESC codes.


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rfka01 Offline OP
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It's ... the Albert!

[Linked Image from i.imgur.com]

[Linked Image from i.imgur.com]

[Linked Image from i.imgur.com]


NCR DMV- DEC Rainbow- Siemens PCD- ITT 3030-Oly People- Acorn A5000- Olivetti M20
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rfka01 Offline OP
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I'm trying to add another Apple II clone mainboard ... if I just re-use another chargen ROM, the text is readable, but this is what I get if I add the ROM that came with the mainboard.

[Linked Image from i.imgur.com]

It looks like the bit order is reversed, and one column is missing.
Is this necessarily a bad dump, or is there a ROM loading parameter that'll correct this presentation of data?


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Different Apple IIs have different font ROM bit orders. The screen_update function for the driver differs in which text update function it calls across different models for that reason. In general, text_update() is IIe/IIc/IIgs order and text_update_orig() is II/II Plus order. For clones, there are IIe clones with II/II Plus video ROMs and vice-versa so things get weird.

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