--- title: Tandy Radio Shack TRS 80 MODEL 4 categories: - Computers types: - Professional Computer origins: - U.S.A. years: - '1983' cpus: - Zilog Z80 params: name: TRS 80 MODEL 4 image: /media/museum/photos/tandy_model4_running_s1.jpg company: /companies/tandy-radio-shack company_name: Tandy Radio Shack specs: - label: NAME value: TRS 80 MODEL 4 - label: MANUFACTURER value: Tandy Radio Shack - label: TYPE value: Professional Computer - label: ORIGIN value: U.S.A. - label: YEAR value: '1983' - label: BUILT IN LANGUAGE value: None - label: KEYBOARD value: Typewriter style 83 keys with numeric keypad - label: CPU value: Zilog Z80 - label: SPEED value: 4 MHz - label: RAM value: 64 KB (up to 128 KB) - label: ROM value: 14 KB - label: TEXT MODES value: 64 x 16 / 32 x 16 / 64 x 40 / 80 x 24 - label: GRAPHIC MODES value: None - label: COLORS value: Monochrome green phosphore - label: SOUND value: Built-in speaker - label: SIZE / WEIGHT value: 47.5 (W) x 52 (D) x 31 (H) cm - label: I/O PORTS value: Tape (500 or 1500 bauds), Centronics, I/O ports compatible with Model III, Serial (4D) - label: BUILT IN MEDIA value: One or Two 5.25'' disk-drives - label: OS value: TRSDOS 6.0 or 1.3, LDOS, CP/M - label: POWER SUPPLY value: Built-in power supply unit - label: PRICE value: |- From $1990. In later years the price came down to about $1000\ By 1990 the Model 4D was being closed out at $599 tabs: - photos - adverts - hardware - emulators - links forum_thread: 254 photos: - title: FIRST VERSION subtitle: '' text: Two Model 4 versions were released. One can recognize them at the surface from the different arrangement of the arrow keys. image: /media/museum/photos/tandy_model4_system_s1.jpg - title: SECOND VERSION subtitle: '' text: |- The second version had an improved gate-array mainboard and a new location for the serial port.\ The arrow keys are now clustered to the right of the keyboard.\ This version features a second 3.5" DS DD 720 KB floppy drive (Tandy option). image: /media/museum/photos/tandy_model4_systemus_s1.jpg - title: MODEL 4 PLATE subtitle: '' text: '' image: /media/museum/photos/tandy_model4_plate_s1.jpg - title: BOTH KEYBOARD VERSIONS subtitle: '' text: '' image: /media/museum/photos/tandy_model4_keyboards_s1.jpg - title: KEYBOARD CLOSE-UP subtitle: '' text: The red button is the Reset switch image: /media/museum/photos/tandy_model4_keybcloseup_s1.jpg - title: SIDE VIEW subtitle: '' text: '' image: /media/museum/photos/tandy_model4_sideview_s1.jpg - title: TOP VIEW subtitle: '' text: '' image: /media/museum/photos/tandy_model4_topview_s1.jpg - title: FRONT PANEL subtitle: '' text: Both FDD drives were Tandon Single-sided, single density models. image: /media/museum/photos/tandy_model4_fdds_s1.jpg - title: BOTTOM SIDE subtitle: '' text: |- **(1)** Parallel printer connector\ **(2)** Serial connector\ **(3)** Expansion port connector\ **(4)** Video adjustment\ **(5)** Tape recorder DIN socket image: /media/museum/photos/tandy_model4_bottomview_s1.jpg - title: 'INSIDE #1' subtitle: '' text: The mainboard is mounted vertically at the back. image: /media/museum/photos/tandy_model4_inside_s1.jpg - title: 'INSIDE #2' subtitle: '' text: The top cover holds the CRT and its electronics. A fan has been added on top of the CRT. image: /media/museum/photos/tandy_model4_topcover_s1.jpg - title: MAINBOARD, 1ST VERSION subtitle: '' text: |- The fist mainboard version used only standard chips. It had 64 KB of RAM. Provision was made for a second 64 KB RAM bank.\ The separate floppy-disk controller card was located behind the mainboard as well as a smal sound generator circuit. image: /media/museum/photos/tandy_model4_mainboard_s2.jpg - title: MAINBOARD, 2ND VERSION subtitle: '' text: |- The second "gate array" version included the floppy-disk controller, the sound generator and buzzer and a second serial port. **(1)** Power connector\ **(2)** Video connector\ **(3)** Tape recorder connector\ **(4)** 128 KB RAM chips (16x4164 equivalents)\ **(5)** WDC1865 UART, serial port controller\ **(6)** WD1773 floppy-disk controller\ **(7)** BIOS ROMs\ **(8)** Z80 CPU socket. In this machine, the CPU chip was replaced by a RAM expansion piggy-back card Other chips were custom made for Tandy and had unknown part numbers. image: /media/museum/photos/tandy_model4_mainboard_s1.jpg - title: RAM CARD subtitle: '' text: This RAM card is inserted on the Z80 CPU socket and provides up to 1 MB of extra RAM (2 x 512 KB DIP modules) used as a virtual floppy-disk drive. image: /media/museum/photos/tandy_model4_ramcard_s1.jpg adverts: - title: US ADVERT, NOV. 1985 subtitle: '' text: '' image: /media/museum/pubs/tandy_model4d_pub_s1.jpg hardware: - title: REMOTE UNIT ACTIVE subtitle: Serial# 26-1210 text: |- This rare unit is meant for teachers to control up to 16 TRS-80 Model 1 from a another TRS-80 equiped with min-disk. All the controled TRS-80 model 1 must be equiped with Level II. It cost 2895fr (France, 1981) image: /media/museum/hardware/tandy_trs80-m1_remote-unit-active.jpg - title: NETWORK II BOX subtitle: p/n 26-1211 text: |- This box allowed up to 16 TRS computer to be networked. Three network boxes were released by Tandy (I, II and III).\ The Network II required verbal communication between the server operator and the remote user, and data transfer had to be completed one user at a time.\ The network III allowed automated control of the network so that users could easily access programs and data stored on the server's storage device. Thanks to **David Sutherland** for the pictures. image: /media/museum/hardware/tandy_network2_s1.jpg - title: DMP-200 subtitle: '' text: 80-column, 100 cps dot matrix printer. image: /media/museum/hardware/tandy_model3_dmp200_s1.jpg - title: DAISY WHEEL PRINTER II subtitle: Serial# 26-1158 text: |- This is a high-quality printer meant to be used with wordprocessors. Some interchangeable daisy-wheels were available (Courrier, Elite, Madeleine). It could print 163 characters per line (34cm), at a 43 cps rate. It cost 9595fr (France, 1981) image: /media/museum/hardware/tandy_trs80-m1_daisy-wheel-printer-2_1.jpg - title: LINE PRINTER I subtitle: Ref# 26-7017 text: |- This printer was a custom version of the Oki Microline 80.\ Printed lower and upper case on paper rolls or listing paper (24cm wide) from 40 to 80 columns/line, at a speed rate of 28 lines/minute. It cost 716 Euros in 1981 (France). image: /media/museum/hardware/tandy_model1_lineprinter1_s1.jpg - title: LINE PRINTER III subtitle: Serial# 26-1156 text: This printer can print lower and upper case, at a speed rate of 120 c/s, on paper up to 38cm wide. It is conceived for intensive use ! It cost 9950fr in 1981 (France). image: /media/museum/hardware/tandy_trs80-m1_line-printer-3_1.jpg - title: LINE PRINTER VI subtitle: Serial# 26-1166 text: |- This large printer can print lower and upper case, graphic characters and symbols at a speed rate of 100 c/s ! This is definately a professional printer. It cost 5495fr in 1981 (France). image: /media/museum/hardware/tandy_trs80-m1_line-printer-6_1.jpg - title: TP-10 THERMAL PRINTER subtitle: Box text: '' image: /media/museum/hardware/tandy_trs80_tp-10_thermal-printer_box.jpg - title: EXATRON subtitle: Stringy Floppy drive text: |- The Exatron Stringy Floppy (ESF) was a low-cost data—storage system that fitted the gap, between cassettes and disk drives.\ The system was based on a miniature endless—loop tape cartridge called a "wafer".\ The amount of data that could be recorded on a wafer depended on the length of tape in it, typically, a 50—foot wafer could hold at least 40 KB of programs or data. **Matt** reports to us:\ A curiousity about the model 1, CPU SPEED had a direct relatonship with STORAGE CAPACITY. if you doubled the clock speed of your MODEL 1 CPU you doubled the amount of data you could store on your stringy floppies. this is a feat that no other computer no matter how many ghz you have in your PC can do today without using compression. Thanks to **David Sutherland** for the pictures image: /media/museum/hardware/tandy_model3_exatronwafer_s1.jpg emulators: - title: David Keil's TRS-80 Model III/4/4P Emulator Page url: http://discover-net.net/~dmkeil/trs80/model4.htm platform: MS DOS text: This program emulates a complete TRS-80 - title: Matthew Reed's TRS-80 Emulator Web Site url: http://www.arrowweb.com/mkr/ platform: MS DOS text: This page offers shareware versions of a TRS-80 Model 4 emulator and a TRS-80 Model 1-2 emulator - title: TRS-80 Model III/4 Emulator url: http://www.vavasour.ca/jeff/trs80.html#model4 platform: MS DOS text: This TRS-80 Model III/4 Emulator is a commercial product - title: Model 4 Emulator url: http://www.arrowweb.com/mkr/ platform: Windows text: '' - title: XTRS for Unix / X url: http://www.research.digital.com/SRC/personal/Tim_Mann/trs80.html platform: Unix / Linux text: '' - title: 'xtrs: TRS-80 Model I/III/4 Emulator for Unix' url: http://www.tim-mann.org/xtrs.html platform: Unix / Linux text: xtrs is a Radio Shack TRS-80 Model I/III/4/4P emulator for Unix and the X Window System - title: TRS-80 Level I BASIC in a browser url: http://www.vavasour.ca/jeff/trs80.html#simulator platform: Other platform text: With this Java emulator, you'll be able to write a BASIC program directly in your browser! - title: Ira Goldklang's TRS-80 Revived Pages url: http://www.trs-80.com/trs80-e.htm platform: Multiplatform text: A complete list of TRS-80 emulators for various platforms ! - title: MESS url: http://www.mess.org platform: Multiplatform text: MESS emulator also emulates a TRS-80 systems links: - title: 8bit-micro.com - Online TRS-80 Computer Magazine url: HTTP://WWW.8BIT-MICRO.COM text: Online Magazine dedicated to the TRS-80 and other Vintage - Monthly Issues - title: David's TRS-80 Page url: http://freespace.virgin.net/david.sampson/ text: '' - title: Ira Goldklang's TRS-80 Revived Pages url: http://www.trs-80.com/ text: Lof of infos about all TRS-80 computers - title: Java TRS-80 Model 1 BASIC Interpreter url: http://ganley.org/software/trs80.html text: '' - title: Mike's Personal Computer Museum url: http://personal.nbnet.nb.ca/mclays/trsmod1.html text: Level 1 & 2 Basic summaries, Tandy time-lines, price-list, etc ... ! - title: RadioShackCatalogs.com url: http://www.RadioShackCatalogs.com text: Here, you can actually/virtually flip-through the pages to view the content of every RadioShack catalog! - title: The TRS-80 Home Page url: http://www.kjsl.com/trs80 text: Full of infos - title: Tim Mann's TRS-80 Page url: http://www.tim-mann.org/trs80.html text: Infos, tools and home of xtrs, a Model I/III/4 emulator for Unix - title: Web Wiz CAPTCHA url: http://www.webwizcaptcha.com text: Discussion about Tandy computers related: - /museum/radionic-model-r1001 - /museum/sysdata-eletronica-jr - /museum/tandy-radio-shack-trs-80-model-12 - /museum/tandy-radio-shack-trs-80-model-16 - /museum/tandy-radio-shack-trs-80-model-4p - /museum/tandy-radio-shack-trs-80-model-i - /museum/tandy-radio-shack-trs-80-model-ii - /museum/tandy-radio-shack-trs-80-model-iii oc_id: 244 source: url: https://web.archive.org/web/20230608082555/http://www.old-computers.com/museum/computer.asp?c=244 date: '2023-06-08' --- The TRS-80 model 4 (ref 26-1068/69) was one of the last models of the TRS-80 series (and perhaps the less known). It ran at 4 MHz and displayed 80 columns x 24 lines in Model 4 mode, but was fully compatible with the [TRS-80 model 3](/museum/tandy-radio-shack-trs-80-model-iii/) and in Model 3 mode actually displayed 64x16 and ran at the Model 3's 2 MHz. It had 64 or 128 KB RAM, the 64 upper KB being used as a ram disk. It had one or two 5.25" floppy disk (184 KB each) and ran under TRSDOS 6.0 or 1.3, LDOS or CP/M. A transformation kit "TRS80 model III -> model IV" was available. The Model 4 was followed by the **Model 4D** (ref. 26-1070). The only difference being double sided drives -384 KB, instead of single sided drives. A portable version of the Model IV called [Model 4P](/museum/tandy-radio-shack-trs-80-model-4p/) (ref. 26-1080) was also marketed few time after. --- **Dwight Briney** specifies:\ A graphics adapter was also available for the Radio Shack TRS-80 Model IV in 1983. It came with a graphics programming language (BASICG). I used BASICG to program a basketball shot chart program that was used for a few seasons until I finally converted it to the IBM compatible Hercules graphics adaptor that had higher resolution.\ It all seems pretty primitive now, but it worked great at the time.