|
Introduction:
|
When I was still in high school there was a TANDY shop in a nearby
shopping centre. I was a (very) regular customer there. Buying sachets
of assorted LEDs, accessories for my (not so legal) radio hobby, and
enjoying the TANDY Catalogue. One day I saw the SHARP PC-1211 there. I
was intrigued but when I found out it didn’t support POKE, PEEK and
CALL, my interest waned. Then came along the PC-2 which did, and I had
to have one. Took some work convincing my father but finally I could buy
the PC-2 and CE-150 pen plotter.
|
|
SHACC:
|
SHACC (SHARP HAnd Computer Club) was a Dutch user club dedicated
to all of SHARP’s Pocket Computers. It had quite a dedicated
user base, club meetings with buns and coffee and loads of Pocket
Computers and peripherals, and AREAD, the club’s magazine.
The club had activities from 1983 but stopped in 1985 due to
waning interest. Some more info on SHACC and downloads of the
AREAD magazine can be found here: PC-1500.info, SHARP clubs : AREAD/SHACC from the
Netherlands (link validated 2024-01-13).
|
|
LeoBAS:
|
When used the way it was meant to be used this Pocket Computer is
powerful enough but machine programming set it free.
One of the
first programs I wrote for that purpose was a BASIC program to
browse through the memory per 16 bytes displaying its ASCII
content and with the ability to POKE memory locations easily. I
dubbed this program ZAP (DEF-Z). Using ZAP
I tried to understand the PC-2’s
memory mapping and when I found it its BASIC command table. The
memory map would be different when a peripheral was attached such
as the CE-150. Its memory block started
with the ASCII character "U" which indicated to the calculator
there was a BASIC command block located. This meant that one could
extend this calculator’s BASIC command set!
It took a big amount of time I was actually meant to do school
work but in the end I managed to write my own set of BASIC
commands. First in memory block &6800 -
&6FFF. How I got memory available in that memory area I do
not remember. Later I created my own memory extension &8000 - &9FFFF using a modified ATARI CMOS RAM
module bought at the Dutch SHACC user club, soldering it in place
using a memory select chip and many unlabeled wires. I now do not
dare open up my PC-2 anymore in fear of
breaking stuff.
In the end I wrote three BASIC command blocks seriously making the
Pocket Computer more powerful. This set, called LeoBAS used memory
block &8800 - &9FFF in !PV mode so it can
not be used unless the PC-2 has been
modified to support that memory block.
Something like the TE-1507 (link validated
2024-01-13) might work but I’m not sure their project is
still alive. It is not possible to modify a regular RAM
module to chip-select in this memory block because the chip-select lines
required are not available on the connector.
My hope is that one day a PC-2/PC-1500 emulator might make it possible to use
this memory block.
My own LeoBAS BASIC command extension includes a new keyboard
routine with auto-repeat and extra function keys. It has an
alternative set of lower case characters because I didn't like the
original set. It has many extra alphanumeric symbols, and all of
these could be plotted using the CE-150
pen plotter as well. There are many handy new BASIC commands for
BASE-n operations, plus handy commands for
graphical functions. See the downloadable manual below.
The final version of my own set of BASIC command additions uses
memory block &8800 - &9FFF bank switched
on !PV. For those interested in experimenting, the block can be
downloaded here:
Download link (revision 20241010) > LeoBAS.
Free to use, but use at your own risk of course. Needs the newer
ROM version on the PC-2/PC-1500A. I have made some changes to the original
1994 revision. One bug fix, and I have changed the shape of the
LeoBAS lower case "f" character.
The original manual I wrote (in Dutch, and please note the
postal address at the end of the manual is no longer valid) can be found
here:
View in new window > LeoBAS Manual 1996.
Download link > LeoBAS Manual 1996.
Please note this early
manual only covers my first memory block &9800 - &9FFF.
Late 2022 I created a revised manual, in English, and
covering the complete set of my BASIC command set. Last
changed on 2024-10-30. Its current fifth revision can be
found here:
View in new window > LeoBAS Manual 2024.
Download link > LeoBAS Manual 2024.
|
|
Emulator:
|
In the period 1989 - 1994 I wrote a PC-2 emulator for the PC-2 on my Mac Plus, in THINK Pascal. Earlier in my life I had an
Apple ][ clone without keyboard and used my PC-2 with a special machine code program as a
keyboard for the Apple ][. It was therefore very easy to make a dump of my
PC-2’s ROM and my own LeoBAS ROM to
a file which I could then transfer to my Mac Plus: I simply
had my PC-2 type its own memory dump to a file on my Apple ][!
It took quite some time and fine tuning and I wrote it as a Desk
Accessory to make multi-tasking less work. The emulation of the
processor was not difficult thanks to all the documentation. I
used the 16 bit lower part of pointers to access the emulated
memory easily. I still have all my THINK Pascal sources and all
the project files, running in SheepShaver, on my modern Mac.
This is a picture of my emulator running in SheepShaver, a Mac OS 9 emulator,
showing the aforementioned ZAP program displaying the memory contents at &9800.
Note the non-standard characters part of LeoBAS. It also runs under UTM on
Macs with Apple Silicon.
Here it is displaying my revised set of lower-case characters.
I really wanted to publish my emulator at the time but did not dare to, due to the
emulator containing the original SHARP ROM code. I didn’t even dare to
use brand names, so mine is called the Radio Shock TRaSh-80.
Compared to PockEmul’s excellent emulator(s) mine was quite rudimentary. No
peripherals, no support for bank switching. It does have support for the clock chip
and interrupts. I am still quite proud of what
I was able to accomplish. After Mac OS 9 died I have not tried to create a modern
version of it which is a pity but there are better alternatives now.
I’m still hoping PockEmul (link validated 2024-01-13) will at one
time make it possible to have a writable and safable memory block
&8800 - &9FFF (or &8000 -
&9FFF for easier chip selecting) for the PC-2 and PC-1500A. That
way I could finally have my own legacy in my back pocket using
PockEmul’s iOS App!
|
