Re: New P112 page

Roger Ivie wrote On 10/21/05 13:05,:
> On 2005-10-21, Scott Moore <samiamsansspam@xxxxxxx> wrote:
>
>>Well, I checked and the $120 price is better than most development
>>boards for the Z80180.
>>
>>However, I question the use of a floppy, even a 3.5, as the media.
>>I assume the software, even Z-system, cannot access more space than
>>available on a floppy (I used to use CP/M with a 40meg hard drive,
>>but that was by taking a lot of liberties with the user number).
>
>
> Well, you're mistaken here; there probably weren't as many liberties
> taken to access the hard disk as you think there were unless you were
> doing it with CP/M 1.4.

Doubt it, since I wrote the Bios.

The reason for the user number stuff was because there is no hierarchy
to the file system, thus the need arose to separate the disk into
different sections so you didn't get one huge directory. The disk
size thing was handled by making very large blocks, a horrible
technique, but worked.

This is all standard stuff, many CP/M hard disk implementations were
managed that way.

>
>>It seems to me that it would make more sense to simply place a flash
>>chip on the board and forgo the floppy interface. Getting rid of
>>the floppy chip would pay for the flash in both real estate and
>>cost terms, and the bios could easily emulate the flash as a drive
>>in software.
>
>
> Dallas Semiconductor makes a nice 512KB battery-backed SRAM module that
> I have my eyes on. Should plug right into one of the RAM sockets. All my
> bookmarks are at work, but I think it was the DS1270Y I had my eye on.
> Make a rip-roaring RAM disk, but will no doubt require some BIOS work.
> Floppies will still come in handing for moving data to and from my
> NetBSD system, however.

The problem is that disc drives are disappearing off new systems, so
the targets to transfer to/from are limited. With burning a CD/DVD somewhat
of a hassle (and too big for the SBC anyways), those flash keyrings are
being used as "todays floppy". The reason I believed that the flash
would be appropriate is that the bios code to run it would actually be
simpler, the flash supplier could preload the runtime code onto the
flash (they use a big autoloading machine), and you can down/up load
the remaining programs from another computer at reasonable rates with
serial or parallel connections.

>
> And there's the expansion connector.
>
> In short, it's a very nice starting place.

.

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