Panasonic JR-300
 | |
| National's October 1983 catalogue: the JR-300 under the TH15-M300 display and television | |
| Specifications | |
|---|---|
| Developer | Matsushita Communication Industrial |
| Manufacturer | Matsushita Electric Industrial (National brand) |
| Type | Personal computer |
| Released | 1984 (schools)[1][2] |
| Intro price | ¥159,000 (main unit)[3] |
| CPU | NEC μPD780C-1 (Z80A), 4 MHz; MN1800A (6802-compatible) sub-processor[2] |
| Memory | 64 KB main RAM; 48 KB graphics RAM; 16 KB sub-processor RAM; 4 KB video RAM; 2 KB shared RAM[3][2] |
| Storage | Cassette, 600 or 2400 baud; optional 5.25-inch floppy unit JR-F01[3][2] |
| Display | Text 80 × 25 or 40 × 25; graphics up to 640 × 200 in 8 colours; digital RGB out[2] |
| Sound | AY-3-8910 PSG, three voices, 8 octaves[2][3] |
| ROM | 8 KB IPL; 16 KB JR-200 BASIC; 16 KB I/O control[3][2] |
| Power | AC 100 V, 50/60 Hz, 28 W[4] |
| Dimensions | Main unit 390 × 350 × 80 mm; keyboard 390 × 198 × 38 mm[3] |
| Weight | Main unit about 4.8 kg; keyboard about 1.6 kg[3] |
| OS / Firmware | JR-ZBASIC 1.0, loaded from cassette[2] |
| Model no. | JR-300 |
The National JR-300 is an 8-bit personal computer developed by Matsushita Communication Industrial and announced by Matsushita Electric Industrial under its National brand in 1983, as the successor to the JR-200.[2][3] It has a Z80A main processor, a separate keyboard, 640 × 200 colour graphics, and a mode that runs JR-200 software on a 6802-compatible second processor. With National's TH15-M300 display and television it could superimpose its output on a television picture and control the set.[2] It was advertised as "Personal Computer & Television 300" (パソコン&テレビ300) at ¥159,000 for the main unit.[5][3]
The JR-300 was not sold in shops. Release was planned for November 1983 and then for March 1984, and the machine is said to have gone to schools and other places of education instead.[2][6]
History
[edit | edit source]The JR series began with the JR-100 (November 1981) and JR-200 (November 1982), compact machines with built-in keyboards that used a television as the display; the JR-200 cost ¥79,800.[2] The JR-300, in National's catalogue of October 1983, was a larger and much more expensive machine with a separate keyboard and a dedicated monitor-television.[7][5] Both tokieng and arch.jpn.org compare its design with Sharp's X1, which had launched in November 1982 with superimposition and television control through its own display.[2][7] Matsushita also launched an MSX computer in October 1983.[2]
National's March 1984 catalogue still showed the JR-300, but it did not reach the shops.[5][2] The writer of arch.jpn.org's JR pages saw only an empty case in an electrical shop and a non-working display unit in the Hanshin department store's showroom, and concluded that it was never sold.[7] Japanese Wikipedia records a showroom prototype that could be started in JR-200 mode.[1] Units did go to schools: the one the shop BEEP exhibited at Maikon Infinite PRO-68K in Akihabara on 13 October 2024, with its operating manual, had come from a school.[2]
Specifications
[edit | edit source]| Item | Specification |
|---|---|
| Main processor | NEC μPD780C-1 (Z80A-compatible), 4 MHz; used in JR-300 mode only |
| Sub-processor | Matsushita MN1800A (6802-compatible): input and output in JR-300 mode, main processor in JR-200 mode |
| Local processors | MN1544, and MN1542 in the keyboard |
| RAM | 64 KB main; 48 KB graphics (main memory of the MN1800A in JR-200 mode); 16 KB sub-processor; 4 KB video; 2 KB shared between the processors; 134 KB in all |
| ROM | 8 KB IPL; 16 KB JR-200 BASIC 5.0; 16 KB I/O control; 40 KB in all |
| Text | 40 × 25 (two pages) or 80 × 25, colour per character; 32 × 24 in JR-200 mode |
| Graphics | 640 × 200 in 8 colours (one page) or monochrome (three pages); 320 × 200 in 8 colours (two pages) or monochrome (six pages); overlays text |
| Sound | AY-3-8910 PSG: three voices, 8 octaves, mixing with an external input; built-in speaker |
| Cassette | 1200/2400 Hz FSK, 600 or 2400 baud, selected by DIP switch |
| Interfaces | Centronics printer; RS-232C, full duplex, 75–9600 baud; floppy disk; external bus; digital RGB out; TV control; audio in and out; joystick (two ports on the keyboard) |
| Keyboard | Separate, sculptured keys, 98 keys with numeric pad, TV control keys and six function keys (12 with SHIFT) |
| Clock | Battery-backed clock chip, able to time peripherals |
| Power | AC 100 V, 50/60 Hz, 28 W |
[2][3][4] National's October 1983 catalogue also listed a 640 × 400 monochrome mode, and gave graphics as 640 × 200 in eight colours and 320 × 200 in three single-colour pages.[3] The operating manual, as recorded by tokieng, lists the modes in the table and not the 640 × 400 mode; he notes that he did not read every page.[2]
Hardware
[edit | edit source]The JR-300 has two processor systems. In JR-300 mode the Z80A runs programs from its own 64 KB, and the MN1800A handles text, the palette, sound and the cassette, exchanging data with the Z80A through 2 KB of shared memory. In JR-200 mode the MN1800A becomes the main processor, using the 48 KB graphics RAM as its memory.[2][8] On the JR-200 the MN1800A and MN1544 were the main and sub processors; on the JR-300 they became the sub and local processors.[7] PocketGriffon, who wrote an emulator from the JR-300's BASIC and demonstration tapes, found that the graphics are drawn by an NEC μPD7220A graphics display controller, and that the Z80A cannot read or write the text or graphics memory directly.[8]
There is no BASIC in ROM for JR-300 mode. The IPL ROM loads a system program at power-on, from a floppy disk, a ROM card or cassette; JR-ZBASIC 1.0 came on the supplied tape, recorded at 2400 and 600 baud, with a demonstration program on the other side. A DIP switch on the back selects the start-up device, JR-200 mode, an automatic mode that tries the main floppy unit, sub floppy unit, ROM card and cassette in turn, or a menu. In JR-200 mode the machine starts JR-200 BASIC 5.0 from ROM, or JR-200 Disk BASIC from the JR-DA01 system disk, and can run at the JR-200's speed or about 1.33 times faster, switched by POKE.[2] Three expansion connectors on the main board sit on the Z80A's bus and take the floppy interface board and the optional kanji ROM card.[2]
Connections
[edit | edit source]
The rear panel carries, from left to right: audio out, the mode DIP switch, audio in, the tape recorder socket, the printer port, the external bus, RS-232C, TV control and RGB out, with the mains lead and rating plate at the right and floppy disk openings above.[4][2] The only video output is digital RGB; a television without an RGB input needs a commercial RF or composite converter.[2] The TV control socket works only with the TH15-M300, through a lead supplied with the set: from BASIC it switches the set on and off, changes channel and volume, turns superimposition on and off, and selects the TV, video or RGB input. The supplied RGB lead also fits National's TX-12M2 and TX-12H2 colour displays.[2] A volume knob on the front sets the built-in speaker and the audio output.[2]
The keyboard connects by cable and has two joystick ports on its back.[2] The supplied accessories were the keyboard and its cable, the RGB lead, a cassette lead with remote control, the operating and BASIC manuals, the JR-ZBASIC and demonstration tape, a function-key template and a label of CTRL-key shortcuts.[2]
Peripherals
[edit | edit source]| Model | Item | Price |
|---|---|---|
| TH15-M300 | 15-inch display and television | ¥139,000 |
| JR-F01 | 5.25-inch floppy disk unit (2D) | ¥129,800 |
| JR-F02 | Additional floppy disk unit (2D) | ¥119,800 |
| JR-F03, JR-F04 | 3.5-inch (?) floppy disk units (2DD) | Not released |
| JR-P01 | Graphic printer (equivalent to the GP-80M) | ¥74,800 |
| TX-12T1 | 12-inch digital colour display | ¥64,800 |
| TH14-NM2G | 14-inch digital colour display | ¥69,800 |
| JH-600 | Voice recognition unit "Panavoice" | ¥135,000 |
| JR-U07 | Joystick (Atari-compatible) | ¥4,980 |
| RQ-8300 | Cassette recorder (2400 baud) | ¥18,000 |
| RQ-8200 | Cassette recorder (600 baud) | ¥15,800 |
| JR-C02, JR-C05, JR-C09 | Printer, RGB and floppy disk cables | ¥4,950, ¥1,900, ¥3,500 |
| JR-DA11 | Ten blank 2D disks | ¥26,000 |
[3] The question mark after 3.5-inch is the list's own. The catalogue also offered an I/O expansion board, expansion RAM, a kanji ROM, a BASIC ROM and an RF converter.[3]
Repair
[edit | edit source]No service manual, schematic or parts list for the JR-300 is available online; the Internet Archive has no JR-300 material. The rating plate gives the mains supply as AC 100 V, 50/60 Hz, 28 W.[4] The clock chip is battery-backed;[3] check any surviving machine for a leaking backup battery before powering it, and see Battery Explosion, Capacitor or Corrosion Damage and Capacitor Failure Symptoms.
Related pages
[edit | edit source]References
[edit | edit source]- ↑ 1.0 1.1 JR (コンピュータ), Wikipedia (Japanese)—link(accessed 2026-10-01) Section JR-300: 1984, ¥159,000, "パソコン&テレビ300", superimposition with the TH15-M300, and a showroom prototype that could start in JR-200 mode; citing ASCII, December 1983, p. 103.
- ↑ 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 2.11 2.12 2.13 2.14 2.15 2.16 2.17 2.18 2.19 2.20 2.21 2.22 2.23 2.24 2.25 2.26 松下電器(ナショナル)の幻のパソコン・JR-300, 20 October 2024—link(accessed 2026-10-01) Notes and photographs from a JR-300 and its operating manual exhibited by the shop BEEP at Maikon Infinite PRO-68K, Akihabara, 13 October 2024: planned release dates, school use, CPU, display modes, memory, ROM, ports, accessories and boot modes.
- ↑ 3.00 3.01 3.02 3.03 3.04 3.05 3.06 3.07 3.08 3.09 3.10 3.11 3.12 3.13 JR series スペック一覧, arch.jpn.org—link(accessed 2026-10-01) Catalogue specifications of the JR-200, JR-800 and JR-300, and a list of JR-series machines and peripherals with model numbers, compatible machines and prices. The JR-300 data are from National's catalogue current at October 1983 (see the companion page cited below).
- ↑ 4.0 4.1 4.2 4.3 Rating plate on the rear of the unit exhibited in 2024, photographed by tokieng: "パーソナルコンピュータ 本体 MODEL JR-300 AC 100V 50/60Hz 28W 松下通信工業株式会社". Hosted as File:National JR-300 rear panel.jpg.
- ↑ 5.0 5.1 5.2 National, パソコン&テレビ300 catalogue, October 1983, cover; photographed with the March 1984 catalogue. Hosted as File:National JR-300 catalogue cover 1983.jpg.
- ↑ Matsushita JR series, Wikipedia—link(accessed 2026-10-01) Section JR-300: delivered mainly to schools, with very few sold to the public.
- ↑ 7.0 7.1 7.2 7.3 謎の機種 "JR.300", arch.jpn.org—link(accessed 2026-10-01) The author's notes on the October 1983 catalogue; he saw only an empty case in a shop and a non-working display unit at the Hanshin department store showroom, and believes the JR-300 was never sold.
- ↑ 8.0 8.1 National JR-300について！, 15 January 2023—link(accessed 2026-10-01) Findings from writing a JR-300 emulator from the machine's BASIC and demonstration tapes: the μPD7220A graphics controller, the division of work between the CPUs, and the memory arrangement. The author marks them as analysis, not confirmed fact.