Help with Apple2 clone "Orange Peel"

From: Dave Dunfield <dave04a_at_dunfield.com>
Date: Sun Jul 18 05:25:47 2004

Hi Tony,

>> So - I have a bit of a paradox : the "2kb/2716" label suggests
>> ROM's, and the 64k of RAM on the mainboard also indicates that
>> all the RAM is on the lower board, however the ROM strings
>> suggest that this may be the only ROM.
>
>IIRC, a real Apple ][ has up to 64K RAM (48K on the mainboard, 16K on a
>language card) and some ROMs. The ROMs are bank-switched with the top 16K
>(Language card) RAM.

That's correct. There are also two language cards, one just has 16k to
replace the ROM's, and one has more memory which can be bank switched
into the 16k ROM address space.

>It sounds like you effectively have a built-in language card (that would
>be quite sensible), and you have RAM in place of the ROM (possibly to get
>round Apple copyrights). The 5517 RAMs take the place of ROMs -- they're
>loaded once on boot-up, and then contain the resident BASIC, etc. The
>EPROM you have sounds like a bootloader for these RAMs.

Thats exactly what I am thinking.

Still trying to figure it out - never gets as far as trying to read the
disk - does chip select the ROM and appear to read some code from it,
but does not make it much further.

Btw, do you (or anyone) have the pinout for 4564 DRAM's? I'm wondering
if they are in backwards (as noted previously, someone "worked" on this
unit) - 16 pins, showing +5 on pin 8 and Gnd on pin 16 - backward to
most chips, although I do recall there were some memory chips with odd
power... Lack of working main RAM would explain it's behavour.

Regards,
Dave
-- 
dave04a (at)    Dave Dunfield
dunfield (dot)  Firmware development services & tools: www.dunfield.com
com             Vintage computing equipment collector.
                http://www.parse.com/~ddunfield/museum/index.html
Received on Sun Jul 18 2004 - 05:25:47 BST

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