apple 2e questions
Mitchell Spector
>I just purchased a cheap enhanced IIe to replace my un-enhanced one & it
>leads to several questions.
>
>1) I read that a revision A motherboard cannot display DHIRES graphics.
That's correct, the original Apple IIe motherboard from January
1983 (820-0064-A) was not capable of displaying Double-Hi-Res graphics.
A few months later Apple began shipping IIe's with a revised motherboard
that had the necessary changes to support DHR mode, also a special video
signal available via slot-7 (820-0064-B). Free upgrades from rev A to B
were made available, but has since been long discontinued I'd suspect.
> My enhanced is an -A dated 1984; my unenhanced is a -B dated 1982.
> Does this mean that apple continued making -A boards 2 years after
> they made -B? Will the new one display DHIRES?
No, Apple only produced the original motherboard for a few months
during 1983. What you have is a third revision IIe motherboard which is
labeled 820-0087-A. For some unexplained reason, Apple used the 'A' label
in this newer revision once again, although functionally it is the same as
the 'B' revision. I think Apple realized this caused confusion, one of my
IIe's had a "820-0064-B" sticker covering the 820-0087-A that was silked
laced on the motherboard. Then again, it came shipped with the unehanced
ROMs (which is unusual) so this could explain it.
Note that Euro-IIe's with a Revision A label (even the oldest made)
can display Double-Hi-Res graphics because of the different circuity used
for a PAL video. Of course the proper motherboard revision is only one
requirement, you also need an Extended 80 columns card (or simular) plugged
into the aux-slot and the jumper installed on the card's pins. The fourth
revision of the IIe motherboard (January 1987), which is easily identified
by it's platinum case, supported DHR out of the box. It had a mini version
of the Extended 80 columns card pre-installed in the aux-slot.
>2) The self-test displays "RAM 0 0 0 0 0 0 0 1 " & the computer crashes
> booting Prodos. Does this mean there is bad RAM? If so, which chip?
Yes, most likely. The "1" indicates a faulty DRAM chip, although
since the 820-0087-A board had most chips soldered in place, replacing it
is going to be more tricky. I'm not sure if the chip on the far right is
bad or if it's reversed, though someone else should be able to tell you.
>3) If because of either 1) or 2) above I decide to simply transfer the
> enhancement chips to my old IIe, can you tell me which 4 chips to
> swap? I know the 65C02. Are the other 3 the VIDEO ROM, CD ROM
> and EF ROM?
You've got it. The 65C02, CD ROM, EF ROM and Video ROM. The
65C02 runs cooler and adds new instructions, CD/EF contain the new
firmware and the video has the Mousetext characters. If the Video
ROM is from an American IIe (rather than Canadian) you might want
to disconnect the wire at J19. This leads to the switch under the
keyboard that lets you switch between the USA and French-Canadian
character set, although leaving it in place isn't a problem (makes
a neat manually invoked screen-blanker on mine ;)
>4) The IIe came with an I/O CONTROLLER 655-0101-B running a DUO DISK.
> Will this controller work with a 3 1/2 " drive?
Definately not. It will only function with the DuoDisk 5.25,
UniDisk 5.25, Apple 5.25 (platinum) and Disk //c 5.25. Or the original
black-front Disk ][, but you'd need an adapter because of the IDC
20-pin connector.
To connect a 3.5" floppy drive requires a different controller
card (ie, UniDisk 3.5/Liron, UDC, PCT or Apple II 3.5 Controller).
>---------------------------------
>David Arnett <bo...@torfree.net>|
> |
>North York, Ontario, Canada. |
Mitchell Spector
spe...@vax2.concordia.ca