Olympia Olytext 20 OS question.

From: Don Maslin <donm_at_cts.com>
Date: Tue Dec 21 23:21:46 1999

On Tue, 21 Dec 1999, Dwight Elvey wrote:

> "Ernest" <ernestls_at_home.com> wrote:
> > Hi Don. I may be able to get a copy of CP/M-80 but it won't be for my
> > specific system. That's the problem. I don't have the OS for it. That's why
> > I was curious about how difficult it would be to set up a generic copy of
> > CP/M to run on it. I've never assembled (?) CP/M for a computer, but I've
> > been reading a how to on doing it, and interested in giving it a shot. I'm
> > not even sure of how to load/run the system monitor to ID the various
> > address' but the thing is, as with anything, there's always a first time,
> > and you have to start somewhere.
> >

To dispell any possible confusion, it is the CCP and BDOS that are the
generic parts of CP/M, abd the BIOS which is machine specific.

                                                 - don
 
> Hi Ernest
> Most of CP/M is generic but the part called BDOS has to
> be specifically written to work on your computer. This
> part contains both the disk, printer, punch and serial I/O.
> The most important are the disk and serial. Usually the
> serial is easy because there were only a limited number
> of serial chips used. You don't have to make the serial
> interrupt driven. It is easier to make it a simple polled
> system at first. I've left mine as a polled system because
> I see no need to setup serial when I'm the only user.
> The disk I/O is a little more difficult. You'll need
> to know how the disk interface works. Most of the newer
> disk interfaces use one of the Western Digital series
> of chips. The reading and writing of sectors is relatively
> easy. You'll still need to have some understanding of
> disk formats and how the sectors are addressed.
> If you can find examples of code for the interfaces you
> have, 95% of the battle is won. You'll need a way of getting
> the code into the memory and then to the disk of your machine
> or someone else with a running machine can create the
> disk. The IMSAIs have the advantage that they have front
> panel switches. The machine may have a ROM based monitor
> that can be handy. If not, you'll need another machine
> to help boot strap your machine. The other machine doesn't
> need to be the same type, it only needs to be able to
> write the same disk format.
> I brought an old IMSAI back to life by doing a BDOS for
> it. It had an AY-3-1015 serial chip that was typical
> of the older machines. These are generally easy to work
> with since there is no software initialization ( other
> than clearing power up trash ) that needs to be done.
> The 8251 and 8250 type parts require initialization
> but they are also more versatile. The disk interface, on
> my machine, was an early TTL interface that had DMA to the
> machines memory. This took me quite a while to figure out
> and it wasn't until I found a schematic that I was able to
> figure it out ( it also was broken ). Luckily for you, most
> of the newer interfaces use standard chips and are easier to
> deal with. In many cases, you can make progress without
> schematics and only the chip manufactures spec sheet.
> It is also possible that many of the functions you need
> are already in ROMs on your machine.
> Dwight
>
>
Received on Tue Dec 21 1999 - 23:21:46 GMT