Programmable Pocket Computers

The world of private computing began 1974 with the programmable pocket computers of US-American companies. Before that there existed only big computers that an ordinary man could not afford.
Here are some of the most remarkable US-American pocket computers of that time (this list is uncomplete):

Programmable pocket computers with volatile memory:

from	picture	model type (display capacity)	RAM + ROM	within this for programs + for data	register (= variables)	external storage
1974		Hewlett Packard HP-65 (15 digits 8-segment)	0.2 KiB RAM + ? KiB ROM	100 byte + 63 byte	9 registers "1"-"9" at 7 byte each in the data memory	magnetic card
1975		Texas Instruments SR-52 (12 digits 8-segment)	0.5 KiB RAM +? KiB ROM	224 byte + 176 byte	22 registers "01"-"19", "99", "98" at 8 byte each in the data memory, plus max. 28 further registers "97"-"70" at the cost of program memory	magnetic card
1976		Hewlett Packard HP-67 (14 digits 8-segment)	0.5 KiB RAM + ? KiB ROM	224 byte + 182 byte	26 registers "A"-"Z" at 7 byte each in the data memory	magnetic card
1977		Texas Instruments TI-58 (12 digits 8-segment)	0.5 KiB RAM + ? KiB ROM (opt. + 5 KiB)	480 byte + 0 byte	max. 60 registers at 8 byte each, in groups of 10 registers at the cost of program memory	-
1977		Texas Instruments TI-59 (12 digits 8-segment)	1 KiB RAM + ? KiB ROM (opt. + 5 KiB)	960 byte + 0 byte	max. 100 registers at 8 byte each, in groups of 10 registers at the cost of program memory (in case of 100 registers 160 byte remain for the program)	magnetic card

RAM = read and write memory, ROM = read only memory
Photos © Hewlett-Packard, © Texas Instruments, each from the original folders

Around 1978 the low power CMOS memory chips (CMOS = complementary metal-oxide semiconductor) spread and very soon the pocket computer manufacturer produced models with non-volatile memory with battery backup, which did not forget their contents even when the computer was powered off. Depending on the manufacturer this feature was called "Constant Memory", "Continuous Memory", "Static Memory", oder similar.

Here are some of the most remarkable pocket computers of that time
(this list is especially uncomplete, because there existed "numberless" programmable models at that time):

Keystroke-programmable pocket computers with non-volatile memory:

from	picture	model type (display capacity)	RAM + ROM	within this for programs + for data	register (= variables)	optional external storage
1979		Texas Instruments TI-58C (12 digits 8-segment)	0.5 KiB RAM + ? KiB ROM	480 byte + 0 byte	up to 60 registers, in groups of 10 registers at the cost of program memory	-
1979		Hewlett Packard HP-41C (12 alphanumerical characters)	0.5 KiB RAM (maximal 2.5 KiB) + 12 KiB ROM	441 byte + 0 byte	up to 63 (max. 319) registers, each register at the cost of program memory	magnetic card
1981		Hewlett Packard HP-41CV (12 alphanumerical characters)	2.5 KiB RAM, (maximal 6.5 KiB) + 12 KiB ROM	2233 byte + 0 byte	up to 319 (max. 922) registers, each register at the cost of program memory	magnetic card
1981		Casio fx-602p (11 alphanum. chars + 3 digits)	0.8 KiB RAM, + ? KiB ROM	512 byte + 176+48 byte	22 registers at 8 byte in the data memory, further 66 registers at the cost of program memory & extra memory (in case of 88 registers 32 byte remain for the program)	audio tape
1983		Hewlett Packard HP-41CX (12 alphanumerical characters)	3.5 KiB RAM, (maximal 6.5 KiB) + 24 KiB ROM	2233+889 byte + 0 byte	up to 319+127 (max. 922) registers, each register at the cost of program memory	magnetic card

RAM = read and write memory, ROM = read only memory
Photos © Hewlett-Packard, © Texas Instruments, from the original folders

In these days the memory used for one floating point number was called "register", and one register at Hewlett-Packard had a size of 7 byte, however at Texas Instruments, Sharp and Casio one register had a size of 8 byte. If the HP-41C (1979) stored letters in one of its registers, a maximum of 6 letters did fit in (one byte serves to define the length of the string), but e.g. on the Sharp PC-1211 (1980, see below) a maximum of 7 letters did fit in.

In 1980, one year after the presentation of the Hewlett-Packard HP-41C, suddenly Japanese companies came up with a new device concept:

While the US-American pocket computers had all functions associated with single keys (one could say they were "keystroke-programmable"), the Japanese decided to provide the high-level programming language BASIC.
While the US-American pocket computers had focused on magnetic cards as external data and program memory (all above-mentioned except the TI-58 had card a reader/writer either built-in or optionally connectable), the Japanese decided to provide optional cassette interfaces, by which it was possible to "chirp" programs and data onto audio tape recorders.

Here are some of the most remarkable Japanese pocket computers of that time (also this list is uncomplete):

BASIC- and C-programmable pocket computers with non-volatile memory:

from	picture	model type (display capacity)	RAM + ROM	within this for programs + for data	register (= variables)	optional external storage
1980		Sharp PC-1210 (24 St. alphanum.)	0.8 KiB RAM + ? KiB ROM	400 byte (BASIC) + 208 byte (data)	26 variables A-Z = A$-Z$ = A(1)-A(26) at 8 byte each in "data", A(27)-A(76) at the cost of program memory	audio tape
1980		Sharp PC-1211 (24 alphanumerical characters)	1.8 KiB RAM + ? KiB ROM	1424 byte (BASIC) + 208 byte (data)	26 variables A-Z = A$-Z$ = A(1)-A(26) at 8 byte each in "data", A(27)-A(204) at the cost of program memory	audio tape
1981		Casio FX-702P (20 alphanumerical characters)	2 KiB RAM (expandable**) + ? KiB ROM	1680 byte (BASIC) + 208 byte (data)	26 variables A-Z = A$-Z$ at 8 byte each in "data", further registers at the cost of program memory	audio tape
1981		Sharp PC-1500 (150 x 7 pixels)	3.5 KiB RAM (maximal 19.5 KiB) + 16 KiB ROM	1850 byte (BASIC) + 624 byte (data)	26 variables A-Z at 8 byte each, and 26 variables A$-Z$ at 16 byte each in "data", further registers at the cost of program memory	audio tape
1983		Sharp PC-1500A (150 x 7 pixels)	8.5 KiB RAM (maximal 24.5 KiB) + 16 KiB ROM	5946 byte (BASIC) + 624 byte (data)	26 variables A-Z at 8 byte each, and 26 variables A$-Z$ at 16 byte each in "data", further registers at the cost of program memory	audio tape
1983		Sharp PC-1245 (16 alphanumerical characters)	2.2 KiB RAM + 24 KiB ROM	1486 byte (BASIC) + 208 byte (data)	26 variables A-Z at 8 byte each, further registers at the cost of program memory	audio tape
1983		Casio PB-700 (160 x 32 pixels)	4 KiB RAM (maximal 16 KiB) + 25 KiB ROM	2864 byte (BASIC) + 208 byte (data)	26 variables A-Z = A$-Z$ at 8 byte each in "data", further registers at the cost of program memory	audio tape
1984		Sharp PC-1350 (150 x 32 pixels)	5 KiB RAM (maximal 21 KiB) + 40 KiB ROM	3070 byte (BASIC) + 208 byte (data)	26 variables A-Z = A$-Z$ = A(1)-A(26) at 8 byte each in "data", further registers at the cost of program memory	audio tape
1986		Casio FX-850P (32 x 2 characters)	8 KiB RAM (maximal 40 KiB) + 128 KiB ROM	1536 byte (BASIC) + 3536 byte* (work)	variables defined within "work", RAM files available at the cost of program memory	audio tape
1986		Sharp PC-1600 (156 x 32 pixels)	16 KiB RAM (maximal 80 KiB) + 96 KiB ROM	12090 byte (BASIC) + 624 byte (data)	26 variables A-Z at 8 byte each, and 26 variables A$-Z$ at 16 byte in "data", further registers at the cost of program memory	audio tape, 2.5"-floppy with 2×64KiB
1989		Casio PB-2000C (192 x 32 pixels)	32 KiB RAM (maximal 64 KiB) + 96 KiB ROM	20992 byte (C) + 1024 byte* (work) + 4095 byte* (file)	variables defined within "work", RAM files within "file", more RAM files or variables at the cost of program memory	audio tape, 3.5"-floppy with 360 KiB
The 16-bit-era of the pocket computers starts: the following models all have a CPU 80L188EB (Intel 80186-compatible)
1991		Casio Z-1 (192 x 32 pixels)	32 KiB RAM (maximal 64 KiB) + 96 KiB ROM ?	18412 byte (C, BASIC) + 6144 byte* (work)	variables defined within "work", RAM files available at the cost of program memory	3.5"-floppy with 640/720/ 1232 KiB
1991		Casio FX-890P (192 x 32 pixels)	64 KiB RAM (maximal 96 KiB) + 96 KiB ROM ?	51180 byte (C, BASIC) + 6144 byte* (work)	variables defined within "work", RAM files available at the cost of program memory	3.5"-floppy with 640/720/ 1232 KiB

RAM = read and write memory, ROM = read only memory, CPU = central processor unit
Photos of the FX-702P, PB-700, PB-2000C: © Casio, photos of the PC-1350 und PC-1600: © Sharp, from the original folders
the other photos © Elmar Duensser, Germany
*: default values, adjustable - in case of larger values the program memory shrinks accordingly
**: the originally planned memory extension for the Casio FX-702P never reached the market

Many old computers fade in our memory (and I have read already various wrong information about them in the Internet), but I havn't forgotten the charm of many of the above mentioned computers - their memory had battery backup that did not forget anything when the computer was powered off - and an operating system that had been debugged already before it was sold publicly, and therefore could be put into a ROM: it was possible to simply switch off such a device, and when it was powered on, it was instantaneously active again - exactly at the location where it had been powered off ! It is a pity that today we have to grapple with slowly booting notebooks, and even the modern PDAs (personal data assistants) with "Pocket Windows" - the modern successors of the pocket computers - need a little time to start ...

Notes to the terms KiB, MiB, PC and compatible

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