The Sharp PC-1246 - A very smol BASIC computer for your 1.2 kb needs.

Since back in my school/apprenticeship days here in Germany, I've had a bit of a weakness for programmable mobile technology. Back in the 80's this basically meant pocket computers.

Not to be confused with the Windows mobile contraptions that came along much later, these were calculators on steroids with a qwerty keyboard*, an alphanumeric LCD display*, RAM and a programming language (usually BASIC*).

The pocket computer market had quite a few entrants, but the two major players were Sharp and Casio. My first Pocket Computer is the one we'll be looking at here, the Sharp PC-1246. 

Pretty little bugger, isn't it?

Sharp PC-1246 Specifications and Information
Released	1982
CPU	SC61720D03 4 Bit CMOS CPU @ 1 MHz (or 576 KHz**)
Memory	20 KB ROM; 2 KB RAM (1278 Bytes user accessible)
Display	16 Character, 7x5 dot matrix, single line alphanumeric LCD Display(Compatible with Sharp PC-1247)
Keyboard         I/O	QWERTY single piece rubber keyboard mat (Compatible with Sharp PC-1247)   11 Pin Sharp serial port
Language	Sharp S’ BASIC

I'm going to be honest, the main reason I bought this particular machine back then was simply because I could afford it. I didn't have my own income yet, so the money for this was scraped together from birthday and Christmas money.  

Now, this might seem a bit hard to believe in these days of Smartphones, but to have a BASIC computer in your pocket was pretty Sci-fi stuff back then. As pocket computers go, the PC-1246 was pretty barebones even back then. 1278 bytes of RAM (better than a ZX 80), a minuscule keyboard with rubber keys (still better than a ZX 80) 

Mmmm, dead flesh keys!

and absolutely no sound output(on par with a ZX 80). Strangely enough, the BASIC BEEP command is implemented, but the actual speaker isn't. You had to get a PC-1247 for that kind of poshness. In accordance with typical Sharp naming conventions, the PC-1246 is a major downgrade from the PC-1245. 

The LCD display is a 16 character affair. Each screen character is made up of a 7x5 dot matrix. There are no lower case letters, and no way to directly access individual pixels using documented BASIC commands. Display contrast is controlled by a wheel on the right side of the unit. 

Itty-bitty squares. You can see that this wasn't a uniform affair.
Ah, the joys of early production LCDs

Yeah, I grew up during the age of Nixie tube and LED displays, to this day, I still find LCD dot matrix screens impressive. 

The PC-1246 is powered by a 4 bit! SC61720D03 CMOS CPU running at 1 MHz (or less), this isn't going to win any speed records, but it will chug through your basic programs at an acceptable pace. Power is supplied by 2 CR2032s, which should keep the little guy running for months, if not years. 

Unscrew the 2 screws holding the lid, and push the battery cover away
 from the direction of the contrast wheel, and you can access the batteries.

As with all Sharp pocket computers, you'll have to switch between "Pro"gramming mode to list and edit your program, and "Run" mode to run a program or use the wee thing as a calculator. Although Sharp pocket computers don't have the same (awesome) separate program areas that their Casio counterparts do, you can help yourself out with labels and the DEF key. In your code, just start with an "A" (or any other character occupying the shaded area of the keyboard) to the beginning of the code you want to jump to. Not remotely as elegant as actually having separate program areas, but better than nothing.

10: "A"

20: PRINT "THIS IS PROGRAM A"

30: GOTO 30
40: "B"

50: PRINT "THIS IS PROGRAM B"

60: GOTO 60

When in RUN mode pressing the DEF key and A or B will execute the respective "programs"

You have 26 numerical and 26 string variables reserved . You can use these without taking away valuable programming space. For anything more exotic***, you'll be forced to DIM these variables first, and there is other variable weirdness you'll want to consult the manual about (I'm looking at you variable A). Not that you'll be writing the next great application on this little guy; line numbers are limited to 1-999. 

Connection to the outside world is provided by an 11 pin I/O port located on the left side of the unit. 

You can connect this up to an optional CE-125 cassette/printer unit, among other things. If you're looking to code your pocket computer programs on a modern PC, you might want to look into using audacity and a few free utilities to do that. 

Finding information for a 38 year old piece of kit can be a very daunting task. I know. Been there done that. I've put together some links that other 1246 owners (or potential owners) might find useful.

Hardware: The PC-1246 is case, display and keyboard compatible with the PC-1247. If you're in a pinch and want to frankenstein a working Pocket Computer together, this information might be of use.

Wikipedia article (actually about Tandy pocket computers, but there are actually a few bits about the PC-1246 in form of the Tandy PC-8)

The service manual (Not the operation manual, this is the techy stuff)

*) There were exceptions.  **) I've seen at least one site that mentions that the Tandy PC-8 (a re-branded PC-1246) ran at 576 kHz. Go figure
***) for example a string variable exceeding 7(!) characters will need to be DIMed first. A variable for holding a 15 character string would look something like this:

10: DIM B$(0)*15 

 This line will also eat up a whopping 34 bytes of RAM!