page_title: TRS-80 Model 4
section_title: Model 4P
hierarchical_section_title: TRS-80 Model 4 / Model 4P
caption_attribution_description: English: Tandy Radio Shack TRS-80 Model 4P
context_page_description: The TRS-80 Model 4 is the last Z80-based home computer family by Radio Shack, sold from April 1983 through autumn 1991.
context_section_description: The Model 4P (September 1983, Radio Shack catalog number 26-1080), is a self-contained luggable unit. It has all the features of the desktop Model 4 except for the ability to add two outboard floppy disk drives and the interface for cassette tape storage (audio sent to the cassette port in Model III mode goes to the internal speaker). It was sold with the two internal single-sided 180KB drives. It was later made with the Gate Array technology (catalog number 26-1080A). 80 Micro published an article describing a simple motherboard modification to enable the installation of two external floppy drives.
  The 4P's CPU board lacks the Model III ROM chips containing the Model III Microsoft BASIC interpreter. Instead the computer is furnished with a floppy disk labelled "Model III/A". This is called the "Model III ROM Image" disk. If the operator wants to boot a Model III DOS, he inserts this disk into the boot drive after powering up. Once it is loaded, he replaces the ROM Image disk with his Model III DOS boot disk and presses reset. From then on the computer behaves exactly like a Model III.
  The 4P's video monitor is 9" in size compared to the Model 4's 12". The smaller size, and sharper dots, produce better video output. The computer is compatible with popular internal Model 4 peripherals, and has a slot for an internal modem board. The Radio Shack modem uses its own proprietary command set and only supports communications at 300 baud. Teletrends produced a 1200 baud that uses the Hayes command set.
  The computer has an internal fan; its compact design does not permit it to use the Model 4's passive cooling.
  Tandy discontinued the 4P by Spring 1985, stating that "even though you won't find a more enthusiastic and devoted group of owners than our Model 4P folks, transportables just weren't moving well for any company that also sold a desktop version".
caption: TRS-80 Model 4P
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