[sebhc] It BOOTS! - but something odd

[Dave Dunfield]

>Are you emulating that RAM area?  Are you also handling the write-protect 
>control via the port and making it unwritable unless enabled by the control?

Ahem -- well -- yes -- I *THOUGHT* that when I implemented
the emulator I allowd RAM writes from 0400-FFFF. I hadn't
bothered to do anything special for the H17 ROM or RAM at
this point. I just used the L=imagefile option to load the
H17 ROM image.

Turns out that I had disallowed writes below 2000, which
means that the H17 RAM was PERMANENTLY write protected -
I'm suprised it got as far as it did.

With the H17 RAM implemented properly, HDOS boots just fine!

But, in testing this, I noticed something REALLY ODD -
perhaps you can shed some light!

With the H17 RAM write protection implemented (ie: you can
only write to the RAM with bit7 of Port7F at 1), then I can
see only 5 files on the disk.

However, with the H17 RAM write protection disabled (ie: you
can write the H17 RAM at any time), then I can see 9 files
on the disk!

In both cases, HDOS does not complain about any errors, and
if you look at the output below, you will see that it thinks
there are no free sectors in the "write protect enabled"
version... ??? ??? ???

==== This is what I get with Write Protect ENABLED ====
HDOS Version 1.6
 Issue # 50.05.00
Date (DD-MMM-YY)? 24-may-99
>dir

Name    .Ext    Size      Date          Flags   24-May-99

ASM     .ABS    28      10-Jun-91
BASIC   .ABS    42      10-Jun-91
DBUG    .ABS    15      10-Jun-91
EDIT    .ABS    17      10-Jun-91
HDOS    .ACM    2       10-Jun-91

   5 Files, Using 104 Sectors (0 Free)
>
==== This is what I get with Write Protect DISABLED ====
HDOS Version 1.6
 Issue # 50.05.00
Date (DD-MMM-YY)? 24-may-99
>dir

Name    .Ext    Size      Date          Flags   24-May-99

ASM     .ABS    28      10-Jun-91
BASIC   .ABS    42      10-Jun-91
DBUG    .ABS    15      10-Jun-91
EDIT    .ABS    17      10-Jun-91
HDOS    .ACM    2       10-Jun-91
INIT    .ABS    20      10-Jun-91
PATCH   .ABS    11      10-Jun-91
SYSGEN  .ABS    14      10-Jun-91
TEST    .ABS    22      10-Jun-91

   9 Files, Using 171 Sectors (30 Free)
>
================================================

Does the write protect bit cover the entire 1K
(1400-17FF) H17 RAM area?

Any other explaination?

Regards,
Dave

-- 
dave04a (at)    Dave Dunfield
dunfield (dot)  Firmware development services & tools: www.dunfield.com
com             Vintage computing equipment collector.
                http://www.parse.com/~ddunfield/museum/index.html

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