<These I/O ports are all 8 bit, right?
<
<Now, an S100 frontpanel would have 16 toggle switches (at least - to
<load a memory address). So why can't you either
You could they didn't and they board was chockfull of crap and a little
more would have made a mess of it.
In 1974 the altair was an "ok" design at best. It was one set of
engineers vision and at that point their best shot. They did it that
way.
Allison
<Was the latter really considered a problem in those days? Or was it
<just that as a result it wasn't real useful to have the front panel do
<that? (Or was it just the additional cost of having the front panel
<do that?)
Fancy way is, cost benefit ratio. It cost a lot! Another was, it's easier
to not do that. Actually it was rare I needed the ability.
Allison
<But what does an instruction do? It just generates bus cycles, right?
<The bus doesn't care whether those cycles come from the CPU or something
<else (unless there's bus mastering and arbitration, which I doubt).
In theory your correct.
<The difference between generating a memory cycle and and I/O cycle on an
<Intel CPU is simply a matter of clocking a different value onto the
<"control bus" (which might be a multiplexed bus, I don't know the 8080
<that well).
Reducing that to practice and at a low cost on S100 bus with an 8080 is a
different matter. To understand that you need to know both as S100 was
not a bidirectional data bus(seperate data in and data out paths) and
all the bus control signals were RAW 8080 status/controls making it a
royal pain to do DMA on the bus. To make a point to do a memory write
on the bus you have to output SWO/, PWR/, MWRITE, SMEMR, SOUT, SINP,
PDBIN and all of them must be in the correct state (some are active
high!). S100 was a poorly designed bus in that respect. I may add that
Altair 8800(a) and Imsai were not bus masters, they were more CPU control.
The best way to descrive this is if the CPU was Not there the front panel
was an ornament.
Allison
At 06:34 PM 2/24/98 PST, you wrote:
>A friend of mine was recently in D.C. and took this
>photo of the Microcomputer exhibit in the Smithsonian
>Museum. I recognize the Altair and the Sol but what
>is the Apple prototype sitting on the table? Here is the
>link to the photo...
Looks like an Apple I to me, but then again I've never seen an actual model
in person.
Hi, I just got back from a hamfest. Found two brand new in the box full
height Tandon floppy drives for the IBM PC. Rich, do you want one?
I also bought two AT&T 3B1 computers without keyboards or monitors. Does
anyone know if the keyboard and monitor from a AT&T 6300 will work on them?
Or where I can find a monitor and keyboard? Also need any advice about
how to get these up and running. What are all the ports for? etc
Joe
While I don't have experience with the Horizon, I think it is similar
(software-wise) to the Advantage (though the Advantage is NOT S100). I
have some software, some for CP/M and some for the NS-DOS. Note that the
floppy disks are hard sectored, impossible to find nowadays and just as
hard to read/write on anything else... (AFAIK - if someone has a program
to do this please speak up!)
Joachim (I usually sign "Joe" but I think that would cause confusion...)
> Joe,
>
> I don't know if software is available but will ask. Does the NS
> horizon use a S-100 bus? I was told the unit I'm (hopefully) about to
>
> acquire has an internal 10MB hard drive. i'm going to go eyeball the
> unit within the next few days.
>
> Marty
>
>
> ______________________________ Reply Separator
> _________________________________
> Subject: Re: North Star Horizon
> Author: classiccmp(a)u.washington.edu at internet
> Date: 2/24/98 1:00 PM
>
>
> Marty,
>
> I have some manuals for the NS Horizon; disk controller, DOS,
> BASIC,
> Pascal. I'm looking for the software.
>
> Joe
>
> At 12:36 PM 2/24/98 -0500, you wrote:
> > Does anybody have any information on a North Star Horizon? I may be
>
> > acquiring one of these soon but don't know much about it except
> that
> > it has wooden side panels and used to support a half-dozen
> terminals.
> > Is it a S-100 bus?
> >
> > Thanks for any help-
> >
> > Marty Mintzell
> >
> >
>
>
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Joe wrote about a Northstar Horizon:
> I think it uses the S-100 bus. According to their manual, North Star
>used the same disk controller in the Horizon that they sold for the S-100
>systems. I have a NS S-100 controller. They are the same electricaly and
>software wise but maybe physically different.
I did some software work on a Horizon many years ago. As I recall, it had
two full height 5.25" bays, a good sized power supply behind the bays (on
the right side) and a shorty S-100 card cage on the left, 8 card slots? But
the NS motherboard also had some logic on the motherboard, at the rear. I
believe there were one or two 8251 serial ports, a baud rate generator,
maybe a parallel port or interrupt controller (look for an Intel 8214 or a
28-pin AMD IC)?
Tony wrote:
>>
>>
>> <But surely this is a limitation of the front panel not the processor.
>> <I/O bus cycles can (easily) be generated from an appropriately designed
>> <front panel.
>>
>> Processor. The 8080 CPU does I/O To/From the accumulator which is
>
>I beg to differ.
>
>All you have to do is to put the CPU into a wait state, tri-state the
>bus buffers and directly drive the address, data and control lines from
>hardware on the frontpanel controller. You can access memory or I/O ports
>that way.
>
In other words, make the front panel do a DMA access, either to memory or an
I/O port? That way it doesn't affect the CPU state at all, except the CPU
has to be running in order to handle the DMA grant.
I finally got the **** thing to boot every time without falling over sideways!
This is a step!
The only problem is, it's still single-user - I still can't get a DZ-11 to work.
I don't think I ever will - I was told you have to kill a 12-pack to get one
to work, and I'm not old enough to buy beer. :)
Anyway, I found an interesting goody in the spare 44 - It's a hex-height
board I recognised from the VAX 750 manual I have. It has 2 50-pin
cables going off to a 16-port EIA distribution panel. It appears to be a DMA
peripheral, it has CA1 and CB1 going off into logic, so I made a DMA slot for
it after the UDA50 in the 2nd BA-11. So, I bring up RSTS - And here's the
result:
Option: HARDWR LIST
Name Address Vector Comments
TT0: 177560 060
RU0: 172150 310 Units: 0(RA81)
KL0: 176510 300 <<< What is that?
KW11L 177546 100
SR 177570 Volatile
DR 177570
Hertz = 60.
Other: FPU, 22-Bit Addressing, Data Space, Cache
-------------------- AFTER THE INSERTION OF THE MODULE -------------------
Option: HARDWR LIST
Name Address Vector Comments
TT0: 177560 060
RU0: 172510 310 Units: 0(RA81)
KL0: 176510 300
DM0: 170500 440 DH0
KW11L 177546 100
SR 177570 Volatile
DR 177570
Herts = 60.
Other: FPU, 22-Bit Addressing, Data Space, Cache
-----------------------------
But when I say START:
KB9:KB24 disabled - no DH0: controller
Does that mean it's broken, or is the Monitor need rebuilt?
Oh, and Tim: The tape drives appear to handle 1600 BPI, but the controllers
don't. I'm gonna dig out my Emulex stuff and see if any of them will handle
this tape.
And wasn't DM0: a disk controller? Am I supposed to reset the CSRs to this?
-------
