backspace with ps/2 keyboard?

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backspace with ps/2 keyboard?

Postby bababooey182 » Aug Sun 14, 2005 10:33 pm

I got my replica 1 powered up for the first time today. I'm using a ps/2 keyboard. I can logically backspace using the underscore character, but the display doesn't actually backspace. It just prints the underscore character. For example "1234_5" is really "1235".

Is this the expected behavior when using a ps/2 keyboard? The manual is ambigous about backspacing.

Thanks!
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Postby vbriel » Aug Mon 15, 2005 6:46 am

Yes, it is operating correctly. The Apple 1 did not have backspace because it used shift registers for its video memory. Since the replica 1 is an attempt to replica the function of the Apple 1, backspace was not created as a function. Hope this helps.
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Postby bababooey182 » Aug Mon 15, 2005 9:55 am

I figured that was the case, but wanted to confirm. I totally agree with your philosophy of replicating exactly. Perhaps a brief note in the Replica 1 manual about how the Apple 1 does backspacing would be worthwhile.

Thnk__anks! :D
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Postby fynch » Aug Mon 15, 2005 11:16 am

Perhaps we could make a replica 2 that adds sound, color, real backspace etc.
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Postby CodeSlapper » Aug Tue 16, 2005 10:33 am

I remember reading about a graphics card that was developed for the expansion slot for the original Apple...
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Postby lucidguppy » Oct Thu 06, 2005 11:13 am

fynch wrote:Perhaps we could make a replica 2 that adds sound, color, real backspace etc.


Yeah its called the apple ][ ;-).

Does anyone know enough asm to allow backspaces on the board?
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Postby vbriel » Oct Thu 06, 2005 4:04 pm

Yeah, it wouldn't take much. I did it just for fun once on my rev B board. What is involved is simply adding the section where it looks for the 0x08 code for back space then I think I left the subtract from cursor position code in the current code. I'll look it up and see.

Now, BASIC has to be modified and I found that by going through and looking for any code the looked for the keyboard and went from there. Only one place has to modified there.

Last, the monitor looks for _ as backspace. Change that byte to 0x08 and the Woz monitor will perform a backspace.

Keep in mind I only did a backspace while on the same line. Going up to the previous line is more difficult. Still, I guess I hacked my own design :shock:

I'll see if I can find the modified code and post it.

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Postby lucidguppy » Oct Fri 07, 2005 7:04 am

awesome!
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