ARM for Apple IIe

[regnirps@aol.com (Regnirps)]

I promised to post the specs of the ARM 7500 chip I have been using in order to
talk about how its features might be integrated into the physical form of an
Apple IIe or //gs either as a card or as a new motherboard that can emulate.

ARM7500 Micro-computer chip with ARM704 32 bit RISK core.
4K byte cache with write buffer
Object oriented MMU
Available in 40 and 60 MHz (VLSI or Cirrus)

32 or 16 bit DRAM and ROM interface.
Sound port.
DMA channels for Video, Cursor, and Sound.
DRAM controller built in.
VGA video or single/dual split LCD interface. (Hey, a IIe with a flip up LCD
screen?)
AT compatible keyboard port.
PS/2 compatible mouse port.
PC compatible Joystick port.
Peripheral bus interface: Modified ISA bus for PC plug in cards and PCMCIA
modules.
IDE drive interface with simple logic.
A PC combo chip gives all the I/O of a PC but we don't fight over IRQs, etc.
One DRAM SIMM could give 32 or 64 meg and soon, 128s will be cheaper.

A bus for using existing Apple cards would not be very hard.

In other words, you can use all the PC hardware without Intel or MicroSoft
involved. The tradeoff possibilities are endless. For example, do we want a VGA
monitor or just write through to Apple video memory and stick with 240x320?

A card or motherboard can easily use the iie keyboard, not so easily the //gs
ADB keyboard, but PC keyboards ar $10 and up.

Reading and writing Apple 3.5 floppies directly would be a programming
challenge, but hardly impossible. Till then, emulate the 6502 code, which is
harder than is sounds, because the IWM requires critical timing. In Apple IIs,
the software instruction timing is part of the disk controller.

What about development? I have an assembler and C compiler for MPW but I don't
know about the legality of spreading it around. There is a GNU c compiler that
runs under LINUX and McLINUX. Metrowerks Codewarrior now supports ARM by
putting the GNU c in their API.

Plus I am twisting the arm of someone to work on porting the absolutely coolest
object oriented programming system ever over to the ARM instruction set.


Charlie Springer