The PHC-20 was released at the same time as the PHC-10 and PHC-25, in 1982. Sanyo wanted to offer a perfect line of products for computing initiation. These three models were supposed to be complementary. But despite high hopes, they just were flops and it's not clear if the PHC-20 was even really sold, as only one or two were found until today. Most pictures found on the net come from press articles from the 80s.
PHC stands for "Personal Home Computer". The PHC-20 was the middle-level system of the trio. It offered an extended version of Tiny Basic stored in ROM. Editing of the program lines is facilitated by the use of the orange arrow keys found at the top right of the keyboard.
The extended Tiny Basic (called Sanyo BASIC) is stored in a 8KB ROM. The computer offers 4KB RAM including 1KB VRAM used for the display, thus leaving only 3KB for the user. Unlike its little brother the PHC-10, the PHC-20 has no sound or music capabilities ! It can display 32 characters by 16 lines in text mode, and has a semi-graphic mode offering a resolution of 64x64 pixels. But the display is monochrome, no colour can be used.
The set of BASIC commands are:
RUN, NEW, LIST, SIZE, RENUM, CSAVE, CLOAD, RETURN, REM, DATA, RESTORE, END, FOR, NEXT, INPUT, PRINT, IF, GOTO, GOSUB, LET, RND, ABS, CLS, LOCATE, PEEK, POKE, INKEY$, PAUSE, GRAPH, PSET, PRESET, POINT
- LOCATE can be used to display texts anywhere on the screen.
- PEEK and POKE are useful to play with values directly in memory locations and is an open door to program in machine language.
- INKEY$ is used to test keyboard entries "on the fly" and thus is very useful to conceive games.
- GRAPH, PSET, PRESET and POINT are used in graphical mode, mainly to display, erase and test a pixel on the screen.
Error reports try to be friendly by displaying message such as :
?? HOW
?? WHAT
?? SORRY
... but that is very obscure and doesn't help at all solving the problem as it doesn't even give the line number incriminated.
Talking about limitations, the computer offer no color display, no sound and its Basic can only handle integers. It could have competed with the Sinclair ZX81 which had the same limitations but it was much more expensive. Thus, the Sanyo PHC-20 is an extremely rare machine and very few were (apparently) ever sold !
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I have an example of this computer.
It was acquired in modern times following an estate sale, so its history is obscure, but it is a working copy in good condition.
I have found the firmware of this machine rather dismal. As your website points out, it can handle integer variables only, which is very limiting. Added to that, it can only deal with variable names of a single character, severely compromising human-friendliness and restricting software to a total of 26 variables. There is no array capability. The ZX81 was a comparative supercomputer next to this little flower!
I located on the Internet exactly one program of any use written in Tiny Basic, which ports to the PHC-20''s Sanyo Basic rather nicely$a "Mastermind"-type guessing game. Having adapted and typed it in, it was successfully stored on tape. The tape dialog is comparatively slick, displaying the names of programs encountered as it searches for the one requested.
The physical tape interface is a 5-pin DIN. The pinout is such that the tape cable for a Radio Shack CoCo 2 can be used, but with the far ends reversed, i.e. the CoCo2 "Mic" line becomes the PHC-20 "Ear" line, and visa versa.
Other than that, I don''t know what to tell you, since I''ve found the system too limiting to play with this machine extensively.
