SWTPC 6800

william degnan billdegnan at gmail.com
Thu Aug 18 06:46:19 CDT 2016

On Aug 18, 2016 12:08 AM, "Brent Hilpert" <hilpert at cs.ubc.ca> wrote:
> On 2016-Aug-17, at 8:26 PM, william degnan wrote:
> >>> No doubt you can get it to work, and it can be a useful ability in
> >>> situations.
> >>> But monitors and loaders tended to be written with different
> >>>
> >>> Monitors targetted interactive use, not receipt of back-to-back
> > characters,
> >>> which would be why you have to add per-char delays.
> >>> The monitor is likely dropping a character or starting a read in the
> > middle
> >>> of one and getting garbage because it went away for too long while
> > looking
> >>> up the command.
> >>> It only has the stop bit period, or even less time, to do processing
> > after
> >>> receipt of a character.
> >>>
> >>> Loaders expect back-to-back characters and are written or optimised
> >>> accordingly, not that one can't still run into problems, which is why
> > the
> >>> checksums can be good.
> >
> > It would be a lot easier if everyone picked top or bottom posting when
> > reply but I digress....
> Yes, we've had that debate a few times.
> AIR, it was decided that bottom-posting was the 'list practice'.
> > My suggestion to use the "monitor method" is a stop-gap just to get to
> > point of loading in something useful when no other means was workinhg.
> > agree any process that has no checksum will be unreliable.  Whatever.. .
> > Let's say for now you have at least the monitor  method until something
> > better comes along.
> But as far as MIKBUG/SWTBUG goes, you also always have the "L" command
with S-record method.
> If the data in your TSC BASIC "M" text were converted to S-record format
- a trivial programming exercise -
> it would be easier (no delays required) (and more reliable) to load into
the SWTP.
> They're both ASCII text input, just different formats.
> I'm not clear why you resorted to the M-command method, was the TSC BASIC
data not originally
> in S-records? - that would be the standard format for loading such
software into an SWTP.

The regular S1 tape exists in a few places, yes use L to load tape.  This
is the best practice.

Purely as an experiment I made a monitor script so I could run at a slow
speed so I could watch the screen as commands were entered.  I can't
remember if it was because the load (L) was not working or if there was a
cpu card issue.

I thought as a first step, given at the time in the flow of the thread the
OP was having issues, my monitor script would be worth trying.


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