12 Oct
2011
12 Oct
'11
2:45 p.m.
Tony Duell wrote:
You have me wondering now! I thought I remembered a Whitechapel ("MG-1
type", i.e. not Hitech-era) machine with SCSI, but I'm not so sure *what*
exactly.
There is no metnion of SCSI in the techncial manual
The mainboard cotnaisn a uPD7261 chip, which is essentially a 'raw' disk
controller often used with ST412 drives. The board also contins the
support circuitry, linked ot the normal 34 pin and 20 pin headers. Much
of the support circuitry is socketed so it can be removed, there's
another header (not well documented in the manual) which conencted to the
drive interface pins of the 7261. It was intended for use with an extenal
data spearator board for SMD drives, but as the manual says, the system
couldn't handle the data rate.
I haev no idea how many pins this data separator connector has, maybe 50
pins. I don';t feel like dismantling my MG1 tonight either...
Thinking
about it, Whitechapel's MG-1 had SCSI on the main PCB as standard
equipment, and that was in 1984, so a couple of years before the Mac Plus.
Does it? I've jeust been through the schematics and I can't find any SCSI
inerface. The hard disk interface is essentially ST412, but there's a
connector allowing acces to the HDC chip pins which was going to be used
for an SMD interface. Problem was, the DMA controller couldn;'t handle
SMD data rates... Going against that though, the wikipedia page (yeah, I
know! :-) for the
I think i trust the techncial manual and schematics more than I trust
Wikipedia...
-tony